1. 01 Apr, 2016 8 commits
  2. 27 Feb, 2016 32 commits
    • Ben Hutchings's avatar
      Linux 3.2.78 · 5aa9ed40
      Ben Hutchings authored
      5aa9ed40
    • Mike Galbraith's avatar
      sched: fix __sched_setscheduler() vs load balancing race · 34bce199
      Mike Galbraith authored
      __sched_setscheduler() may release rq->lock in pull_rt_task() as a task is
      being changed rt -> fair class.  load balancing may sneak in, move the task
      behind __sched_setscheduler()'s back, which explodes in switched_to_fair()
      when the passed but no longer valid rq is used.  Tell can_migrate_task() to
      say no if ->pi_lock is held.
      
      @stable: Kernels that predate SCHED_DEADLINE can use this simple (and tested)
      check in lieu of backport of the full 18 patch mainline treatment.
      Signed-off-by: default avatarMike Galbraith <umgwanakikbuti@gmail.com>
      [bwh: Backported to 3.2:
       - Adjust numbering in the comment
       - Adjust filename]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      Cc: Byungchul Park <byungchul.park@lge.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Willy Tarreau <w@1wt.eu>
      34bce199
    • Ben Hutchings's avatar
      pipe: Fix buffer offset after partially failed read · feae3ca2
      Ben Hutchings authored
      Quoting the RHEL advisory:
      
      > It was found that the fix for CVE-2015-1805 incorrectly kept buffer
      > offset and buffer length in sync on a failed atomic read, potentially
      > resulting in a pipe buffer state corruption. A local, unprivileged user
      > could use this flaw to crash the system or leak kernel memory to user
      > space. (CVE-2016-0774, Moderate)
      
      The same flawed fix was applied to stable branches from 2.6.32.y to
      3.14.y inclusive, and I was able to reproduce the issue on 3.2.y.
      We need to give pipe_iov_copy_to_user() a separate offset variable
      and only update the buffer offset if it succeeds.
      
      References: https://rhn.redhat.com/errata/RHSA-2016-0103.htmlSigned-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      feae3ca2
    • Hariprasad S's avatar
      iw_cxgb3: Fix incorrectly returning error on success · 4249217f
      Hariprasad S authored
      commit 67f1aee6 upstream.
      
      The cxgb3_*_send() functions return NET_XMIT_ values, which are
      positive integers values. So don't treat positive return values
      as an error.
      Signed-off-by: default avatarSteve Wise <swise@opengridcomputing.com>
      Signed-off-by: default avatarHariprasad Shenai <hariprasad@chelsio.com>
      Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      4249217f
    • Willy Tarreau's avatar
      pipe: limit the per-user amount of pages allocated in pipes · 92375b85
      Willy Tarreau authored
      commit 759c0114 upstream.
      
      On no-so-small systems, it is possible for a single process to cause an
      OOM condition by filling large pipes with data that are never read. A
      typical process filling 4000 pipes with 1 MB of data will use 4 GB of
      memory. On small systems it may be tricky to set the pipe max size to
      prevent this from happening.
      
      This patch makes it possible to enforce a per-user soft limit above
      which new pipes will be limited to a single page, effectively limiting
      them to 4 kB each, as well as a hard limit above which no new pipes may
      be created for this user. This has the effect of protecting the system
      against memory abuse without hurting other users, and still allowing
      pipes to work correctly though with less data at once.
      
      The limit are controlled by two new sysctls : pipe-user-pages-soft, and
      pipe-user-pages-hard. Both may be disabled by setting them to zero. The
      default soft limit allows the default number of FDs per process (1024)
      to create pipes of the default size (64kB), thus reaching a limit of 64MB
      before starting to create only smaller pipes. With 256 processes limited
      to 1024 FDs each, this results in 1024*64kB + (256*1024 - 1024) * 4kB =
      1084 MB of memory allocated for a user. The hard limit is disabled by
      default to avoid breaking existing applications that make intensive use
      of pipes (eg: for splicing).
      
      Reported-by: socketpair@gmail.com
      Reported-by: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
      Mitigates: CVE-2013-4312 (Linux 2.0+)
      Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarWilly Tarreau <w@1wt.eu>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      [bwh: Backported to 3.2: adjust context]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      92375b85
    • Hannes Frederic Sowa's avatar
      unix: correctly track in-flight fds in sending process user_struct · 5ea82004
      Hannes Frederic Sowa authored
      commit 415e3d3e upstream.
      
      The commit referenced in the Fixes tag incorrectly accounted the number
      of in-flight fds over a unix domain socket to the original opener
      of the file-descriptor. This allows another process to arbitrary
      deplete the original file-openers resource limit for the maximum of
      open files. Instead the sending processes and its struct cred should
      be credited.
      
      To do so, we add a reference counted struct user_struct pointer to the
      scm_fp_list and use it to account for the number of inflight unix fds.
      
      Fixes: 712f4aad ("unix: properly account for FDs passed over unix sockets")
      Reported-by: default avatarDavid Herrmann <dh.herrmann@gmail.com>
      Cc: David Herrmann <dh.herrmann@gmail.com>
      Cc: Willy Tarreau <w@1wt.eu>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      [bwh: Backported to 3.2: adjust context]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      5ea82004
    • willy tarreau's avatar
      unix: properly account for FDs passed over unix sockets · a5a6cf8c
      willy tarreau authored
      commit 712f4aad upstream.
      
      It is possible for a process to allocate and accumulate far more FDs than
      the process' limit by sending them over a unix socket then closing them
      to keep the process' fd count low.
      
      This change addresses this problem by keeping track of the number of FDs
      in flight per user and preventing non-privileged processes from having
      more FDs in flight than their configured FD limit.
      
      Reported-by: socketpair@gmail.com
      Reported-by: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
      Mitigates: CVE-2013-4312 (Linux 2.0+)
      Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Acked-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
      Signed-off-by: default avatarWilly Tarreau <w@1wt.eu>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      [carnil: Backported to 3.16: adjust context]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      a5a6cf8c
    • Andrey Konovalov's avatar
      ALSA: usb-audio: avoid freeing umidi object twice · 78a6b3f7
      Andrey Konovalov authored
      commit 07d86ca9 upstream.
      
      The 'umidi' object will be free'd on the error path by snd_usbmidi_free()
      when tearing down the rawmidi interface. So we shouldn't try to free it
      in snd_usbmidi_create() after having registered the rawmidi interface.
      
      Found by KASAN.
      Signed-off-by: default avatarAndrey Konovalov <andreyknvl@gmail.com>
      Acked-by: default avatarClemens Ladisch <clemens@ladisch.de>
      Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      78a6b3f7
    • David Sterba's avatar
      btrfs: properly set the termination value of ctx->pos in readdir · 57ce5761
      David Sterba authored
      commit bc4ef759 upstream.
      
      The value of ctx->pos in the last readdir call is supposed to be set to
      INT_MAX due to 32bit compatibility, unless 'pos' is intentially set to a
      larger value, then it's LLONG_MAX.
      
      There's a report from PaX SIZE_OVERFLOW plugin that "ctx->pos++"
      overflows (https://forums.grsecurity.net/viewtopic.php?f=1&t=4284), on a
      64bit arch, where the value is 0x7fffffffffffffff ie. LLONG_MAX before
      the increment.
      
      We can get to that situation like that:
      
      * emit all regular readdir entries
      * still in the same call to readdir, bump the last pos to INT_MAX
      * next call to readdir will not emit any entries, but will reach the
        bump code again, finds pos to be INT_MAX and sets it to LLONG_MAX
      
      Normally this is not a problem, but if we call readdir again, we'll find
      'pos' set to LLONG_MAX and the unconditional increment will overflow.
      
      The report from Victor at
      (http://thread.gmane.org/gmane.comp.file-systems.btrfs/49500) with debugging
      print shows that pattern:
      
       Overflow: e
       Overflow: 7fffffff
       Overflow: 7fffffffffffffff
       PAX: size overflow detected in function btrfs_real_readdir
         fs/btrfs/inode.c:5760 cicus.935_282 max, count: 9, decl: pos; num: 0;
         context: dir_context;
       CPU: 0 PID: 2630 Comm: polkitd Not tainted 4.2.3-grsec #1
       Hardware name: Gigabyte Technology Co., Ltd. H81ND2H/H81ND2H, BIOS F3 08/11/2015
        ffffffff81901608 0000000000000000 ffffffff819015e6 ffffc90004973d48
        ffffffff81742f0f 0000000000000007 ffffffff81901608 ffffc90004973d78
        ffffffff811cb706 0000000000000000 ffff8800d47359e0 ffffc90004973ed8
       Call Trace:
        [<ffffffff81742f0f>] dump_stack+0x4c/0x7f
        [<ffffffff811cb706>] report_size_overflow+0x36/0x40
        [<ffffffff812ef0bc>] btrfs_real_readdir+0x69c/0x6d0
        [<ffffffff811dafc8>] iterate_dir+0xa8/0x150
        [<ffffffff811e6d8d>] ? __fget_light+0x2d/0x70
        [<ffffffff811dba3a>] SyS_getdents+0xba/0x1c0
       Overflow: 1a
        [<ffffffff811db070>] ? iterate_dir+0x150/0x150
        [<ffffffff81749b69>] entry_SYSCALL_64_fastpath+0x12/0x83
      
      The jump from 7fffffff to 7fffffffffffffff happens when new dir entries
      are not yet synced and are processed from the delayed list. Then the code
      could go to the bump section again even though it might not emit any new
      dir entries from the delayed list.
      
      The fix avoids entering the "bump" section again once we've finished
      emitting the entries, both for synced and delayed entries.
      
      References: https://forums.grsecurity.net/viewtopic.php?f=1&t=4284Reported-by: default avatarVictor <services@swwu.com>
      Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
      Tested-by: default avatarHolger Hoffstätte <holger.hoffstaette@googlemail.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      [bwh: Backported to 3.2:
       - s/ctx->pos/filp->f_pos/
       - Adjust context]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      57ce5761
    • Linus Walleij's avatar
      ARM: 8519/1: ICST: try other dividends than 1 · 915fb5e3
      Linus Walleij authored
      commit e972c374 upstream.
      
      Since the dawn of time the ICST code has only supported divide
      by one or hang in an eternal loop. Luckily we were always dividing
      by one because the reference frequency for the systems using
      the ICSTs is 24MHz and the [min,max] values for the PLL input
      if [10,320] MHz for ICST307 and [6,200] for ICST525, so the loop
      will always terminate immediately without assigning any divisor
      for the reference frequency.
      
      But for the code to make sense, let's insert the missing i++
      Reported-by: default avatarDavid Binderman <dcb314@hotmail.com>
      Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
      Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      915fb5e3
    • Alexandra Yates's avatar
      ahci: Intel DNV device IDs SATA · fe9f7e71
      Alexandra Yates authored
      commit 342decff upstream.
      
      Adding Intel codename DNV platform device IDs for SATA.
      Signed-off-by: default avatarAlexandra Yates <alexandra.yates@linux.intel.com>
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      fe9f7e71
    • Takashi Iwai's avatar
      ALSA: timer: Fix race at concurrent reads · c65409e6
      Takashi Iwai authored
      commit 4dff5c7b upstream.
      
      snd_timer_user_read() has a potential race among parallel reads, as
      qhead and qused are updated outside the critical section due to
      copy_to_user() calls.  Move them into the critical section, and also
      sanitize the relevant code a bit.
      Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
      [bwh: Backported to 3.2: there's no check for tu->connected to fix up]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      c65409e6
    • Takashi Iwai's avatar
      ALSA: timer: Fix race between stop and interrupt · 8470405c
      Takashi Iwai authored
      commit ed8b1d6d upstream.
      
      A slave timer element also unlinks at snd_timer_stop() but it takes
      only slave_active_lock.  When a slave is assigned to a master,
      however, this may become a race against the master's interrupt
      handling, eventually resulting in a list corruption.  The actual bug
      could be seen with a syzkaller fuzzer test case in BugLink below.
      
      As a fix, we need to take timeri->timer->lock when timer isn't NULL,
      i.e. assigned to a master, while the assignment to a master itself is
      protected by slave_active_lock.
      
      BugLink: http://lkml.kernel.org/r/CACT4Y+Y_Bm+7epAb=8Wi=AaWd+DYS7qawX52qxdCfOfY49vozQ@mail.gmail.comSigned-off-by: default avatarTakashi Iwai <tiwai@suse.de>
      [bwh: Backported to 3.2: adjust context, indentation]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      8470405c
    • Xin Long's avatar
      sctp: translate network order to host order when users get a hmacid · 152e8fcb
      Xin Long authored
      commit 7a84bd46 upstream.
      
      Commit ed5a377d ("sctp: translate host order to network order when
      setting a hmacid") corrected the hmacid byte-order when setting a hmacid.
      but the same issue also exists on getting a hmacid.
      
      We fix it by changing hmacids to host order when users get them with
      getsockopt.
      
      Fixes: Commit ed5a377d ("sctp: translate host order to network order when setting a hmacid")
      Signed-off-by: default avatarXin Long <lucien.xin@gmail.com>
      Acked-by: default avatarMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      152e8fcb
    • Linus Walleij's avatar
      ARM: 8517/1: ICST: avoid arithmetic overflow in icst_hz() · ece1929f
      Linus Walleij authored
      commit 5070fb14 upstream.
      
      When trying to set the ICST 307 clock to 25174000 Hz I ran into
      this arithmetic error: the icst_hz_to_vco() correctly figure out
      DIVIDE=2, RDW=100 and VDW=99 yielding a frequency of
      25174000 Hz out of the VCO. (I replicated the icst_hz() function
      in a spreadsheet to verify this.)
      
      However, when I called icst_hz() on these VCO settings it would
      instead return 4122709 Hz. This causes an error in the common
      clock driver for ICST as the common clock framework will call
      .round_rate() on the clock which will utilize icst_hz_to_vco()
      followed by icst_hz() suggesting the erroneous frequency, and
      then the clock gets set to this.
      
      The error did not manifest in the old clock framework since
      this high frequency was only used by the CLCD, which calls
      clk_set_rate() without first calling clk_round_rate() and since
      the old clock framework would not call clk_round_rate() before
      setting the frequency, the correct values propagated into
      the VCO.
      
      After some experimenting I figured out that it was due to a simple
      arithmetic overflow: the divisor for 24Mhz reference frequency
      as reference becomes 24000000*2*(99+8)=0x132212400 and the "1"
      in bit 32 overflows and is lost.
      
      But introducing an explicit 64-by-32 bit do_div() and casting
      the divisor into (u64) we get the right frequency back, and the
      right frequency gets set.
      
      Tested on the ARM Versatile.
      
      Cc: linux-clk@vger.kernel.org
      Cc: Pawel Moll <pawel.moll@arm.com>
      Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
      Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      ece1929f
    • Takashi Iwai's avatar
      ALSA: timer: Fix wrong instance passed to slave callbacks · 20e86609
      Takashi Iwai authored
      commit 117159f0 upstream.
      
      In snd_timer_notify1(), the wrong timer instance was passed for slave
      ccallback function.  This leads to the access to the wrong data when
      an incompatible master is handled (e.g. the master is the sequencer
      timer and the slave is a user timer), as spotted by syzkaller fuzzer.
      
      This patch fixes that wrong assignment.
      
      BugLink: http://lkml.kernel.org/r/CACT4Y+Y_Bm+7epAb=8Wi=AaWd+DYS7qawX52qxdCfOfY49vozQ@mail.gmail.comReported-by: default avatarDmitry Vyukov <dvyukov@google.com>
      Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      20e86609
    • Takashi Iwai's avatar
      ALSA: dummy: Implement timer backend switching more safely · 98aa5568
      Takashi Iwai authored
      commit ddce57a6 upstream.
      
      Currently the selected timer backend is referred at any moment from
      the running PCM callbacks.  When the backend is switched, it's
      possible to lead to inconsistency from the running backend.  This was
      pointed by syzkaller fuzzer, and the commit [7ee96216: ALSA:
      dummy: Disable switching timer backend via sysfs] disabled the dynamic
      switching for avoiding the crash.
      
      This patch improves the handling of timer backend switching.  It keeps
      the reference to the selected backend during the whole operation of an
      opened stream so that it won't be changed by other streams.
      
      Together with this change, the hrtimer parameter is reenabled as
      writable now.
      
      NOTE: this patch also turned out to fix the still remaining race.
      Namely, ops was still replaced dynamically at dummy_pcm_open:
      
        static int dummy_pcm_open(struct snd_pcm_substream *substream)
        {
        ....
                dummy->timer_ops = &dummy_systimer_ops;
                if (hrtimer)
                        dummy->timer_ops = &dummy_hrtimer_ops;
      
      Since dummy->timer_ops is common among all streams, and when the
      replacement happens during accesses of other streams, it may lead to a
      crash.  This was actually triggered by syzkaller fuzzer and KASAN.
      
      This patch rewrites the code not to use the ops shared by all streams
      any longer, too.
      
      BugLink: http://lkml.kernel.org/r/CACT4Y+aZ+xisrpuM6cOXbL21DuM0yVxPYXf4cD4Md9uw0C3dBQ@mail.gmail.comReported-by: default avatarDmitry Vyukov <dvyukov@google.com>
      Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
      [bwh: Backported to 3.2: adjust context]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      98aa5568
    • James Bottomley's avatar
      klist: fix starting point removed bug in klist iterators · c1783868
      James Bottomley authored
      commit 00cd29b7 upstream.
      
      The starting node for a klist iteration is often passed in from
      somewhere way above the klist infrastructure, meaning there's no
      guarantee the node is still on the list.  We've seen this in SCSI where
      we use bus_find_device() to iterate through a list of devices.  In the
      face of heavy hotplug activity, the last device returned by
      bus_find_device() can be removed before the next call.  This leads to
      
      Dec  3 13:22:02 localhost kernel: WARNING: CPU: 2 PID: 28073 at include/linux/kref.h:47 klist_iter_init_node+0x3d/0x50()
      Dec  3 13:22:02 localhost kernel: Modules linked in: scsi_debug x86_pkg_temp_thermal kvm_intel kvm irqbypass crc32c_intel joydev iTCO_wdt dcdbas ipmi_devintf acpi_power_meter iTCO_vendor_support ipmi_si imsghandler pcspkr wmi acpi_cpufreq tpm_tis tpm shpchp lpc_ich mfd_core nfsd nfs_acl lockd grace sunrpc tg3 ptp pps_core
      Dec  3 13:22:02 localhost kernel: CPU: 2 PID: 28073 Comm: cat Not tainted 4.4.0-rc1+ #2
      Dec  3 13:22:02 localhost kernel: Hardware name: Dell Inc. PowerEdge R320/08VT7V, BIOS 2.0.22 11/19/2013
      Dec  3 13:22:02 localhost kernel: ffffffff81a20e77 ffff880613acfd18 ffffffff81321eef 0000000000000000
      Dec  3 13:22:02 localhost kernel: ffff880613acfd50 ffffffff8107ca52 ffff88061176b198 0000000000000000
      Dec  3 13:22:02 localhost kernel: ffffffff814542b0 ffff880610cfb100 ffff88061176b198 ffff880613acfd60
      Dec  3 13:22:02 localhost kernel: Call Trace:
      Dec  3 13:22:02 localhost kernel: [<ffffffff81321eef>] dump_stack+0x44/0x55
      Dec  3 13:22:02 localhost kernel: [<ffffffff8107ca52>] warn_slowpath_common+0x82/0xc0
      Dec  3 13:22:02 localhost kernel: [<ffffffff814542b0>] ? proc_scsi_show+0x20/0x20
      Dec  3 13:22:02 localhost kernel: [<ffffffff8107cb4a>] warn_slowpath_null+0x1a/0x20
      Dec  3 13:22:02 localhost kernel: [<ffffffff8167225d>] klist_iter_init_node+0x3d/0x50
      Dec  3 13:22:02 localhost kernel: [<ffffffff81421d41>] bus_find_device+0x51/0xb0
      Dec  3 13:22:02 localhost kernel: [<ffffffff814545ad>] scsi_seq_next+0x2d/0x40
      [...]
      
      And an eventual crash. It can actually occur in any hotplug system
      which has a device finder and a starting device.
      
      We can fix this globally by making sure the starting node for
      klist_iter_init_node() is actually a member of the list before using it
      (and by starting from the beginning if it isn't).
      Reported-by: default avatarEwan D. Milne <emilne@redhat.com>
      Tested-by: default avatarEwan D. Milne <emilne@redhat.com>
      Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      c1783868
    • Herbert Xu's avatar
      crypto: algif_skcipher - Do not dereference ctx without socket lock · c54ddfbb
      Herbert Xu authored
      commit 6454c2b8 upstream.
      
      Any access to non-constant bits of the private context must be
      done under the socket lock, in particular, this includes ctx->req.
      
      This patch moves such accesses under the lock, and fetches the
      tfm from the parent socket which is guaranteed to be constant,
      rather than from ctx->req.
      Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
      [bwh: Backported to 3.2:
       - Drop changes to skcipher_recvmsg_async
       - s/skcipher/ablkcipher/ in many places
       - s/skc->skcipher/skc->base/]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      c54ddfbb
    • Mathias Krause's avatar
      crypto: user - lock crypto_alg_list on alg dump · cc058b6f
      Mathias Krause authored
      commit 63e41ebc upstream.
      
      We miss to take the crypto_alg_sem semaphore when traversing the
      crypto_alg_list for CRYPTO_MSG_GETALG dumps. This allows a race with
      crypto_unregister_alg() removing algorithms from the list while we're
      still traversing it, thereby leading to a use-after-free as show below:
      
      [ 3482.071639] general protection fault: 0000 [#1] SMP
      [ 3482.075639] Modules linked in: aes_x86_64 glue_helper lrw ablk_helper cryptd gf128mul ipv6 pcspkr serio_raw virtio_net microcode virtio_pci virtio_ring virtio sr_mod cdrom [last unloaded: aesni_intel]
      [ 3482.075639] CPU: 1 PID: 11065 Comm: crconf Not tainted 4.3.4-grsec+ #126
      [ 3482.075639] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014
      [ 3482.075639] task: ffff88001cd41a40 ti: ffff88001cd422c8 task.ti: ffff88001cd422c8
      [ 3482.075639] RIP: 0010:[<ffffffff93722bd3>]  [<ffffffff93722bd3>] strncpy+0x13/0x30
      [ 3482.075639] RSP: 0018:ffff88001f713b60  EFLAGS: 00010202
      [ 3482.075639] RAX: ffff88001f6c4430 RBX: ffff88001f6c43a0 RCX: ffff88001f6c4430
      [ 3482.075639] RDX: 0000000000000040 RSI: fefefefefefeff16 RDI: ffff88001f6c4430
      [ 3482.075639] RBP: ffff88001f713b60 R08: ffff88001f6c4470 R09: ffff88001f6c4480
      [ 3482.075639] R10: 0000000000000002 R11: 0000000000000246 R12: ffff88001ce2aa28
      [ 3482.075639] R13: ffff880000093700 R14: ffff88001f5e4bf8 R15: 0000000000003b20
      [ 3482.075639] FS:  0000033826fa2700(0000) GS:ffff88001e900000(0000) knlGS:0000000000000000
      [ 3482.075639] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
      [ 3482.075639] CR2: ffffffffff600400 CR3: 00000000139ec000 CR4: 00000000001606f0
      [ 3482.075639] Stack:
      [ 3482.075639]  ffff88001f713bd8 ffffffff936ccd00 ffff88001e5c4200 ffff880000093700
      [ 3482.075639]  ffff88001f713bd0 ffffffff938ef4bf 0000000000000000 0000000000003b20
      [ 3482.075639]  ffff88001f5e4bf8 ffff88001f5e4848 0000000000000000 0000000000003b20
      [ 3482.075639] Call Trace:
      [ 3482.075639]  [<ffffffff936ccd00>] crypto_report_alg+0xc0/0x3e0
      [ 3482.075639]  [<ffffffff938ef4bf>] ? __alloc_skb+0x16f/0x300
      [ 3482.075639]  [<ffffffff936cd08a>] crypto_dump_report+0x6a/0x90
      [ 3482.075639]  [<ffffffff93935707>] netlink_dump+0x147/0x2e0
      [ 3482.075639]  [<ffffffff93935f99>] __netlink_dump_start+0x159/0x190
      [ 3482.075639]  [<ffffffff936ccb13>] crypto_user_rcv_msg+0xc3/0x130
      [ 3482.075639]  [<ffffffff936cd020>] ? crypto_report_alg+0x3e0/0x3e0
      [ 3482.075639]  [<ffffffff936cc4b0>] ? alg_test_crc32c+0x120/0x120
      [ 3482.075639]  [<ffffffff93933145>] ? __netlink_lookup+0xd5/0x120
      [ 3482.075639]  [<ffffffff936cca50>] ? crypto_add_alg+0x1d0/0x1d0
      [ 3482.075639]  [<ffffffff93938141>] netlink_rcv_skb+0xe1/0x130
      [ 3482.075639]  [<ffffffff936cc4f8>] crypto_netlink_rcv+0x28/0x40
      [ 3482.075639]  [<ffffffff939375a8>] netlink_unicast+0x108/0x180
      [ 3482.075639]  [<ffffffff93937c21>] netlink_sendmsg+0x541/0x770
      [ 3482.075639]  [<ffffffff938e31e1>] sock_sendmsg+0x21/0x40
      [ 3482.075639]  [<ffffffff938e4763>] SyS_sendto+0xf3/0x130
      [ 3482.075639]  [<ffffffff93444203>] ? bad_area_nosemaphore+0x13/0x20
      [ 3482.075639]  [<ffffffff93444470>] ? __do_page_fault+0x80/0x3a0
      [ 3482.075639]  [<ffffffff939d80cb>] entry_SYSCALL_64_fastpath+0x12/0x6e
      [ 3482.075639] Code: 88 4a ff 75 ed 5d 48 0f ba 2c 24 3f c3 66 66 2e 0f 1f 84 00 00 00 00 00 55 48 85 d2 48 89 f8 48 89 f9 4c 8d 04 17 48 89 e5 74 15 <0f> b6 16 80 fa 01 88 11 48 83 de ff 48 83 c1 01 4c 39 c1 75 eb
      [ 3482.075639] RIP  [<ffffffff93722bd3>] strncpy+0x13/0x30
      
      To trigger the race run the following loops simultaneously for a while:
        $ while : ; do modprobe aesni-intel; rmmod aesni-intel; done
        $ while : ; do crconf show all > /dev/null; done
      
      Fix the race by taking the crypto_alg_sem read lock, thereby preventing
      crypto_unregister_alg() from modifying the algorithm list during the
      dump.
      
      This bug has been detected by the PaX memory sanitize feature.
      Signed-off-by: default avatarMathias Krause <minipli@googlemail.com>
      Cc: Steffen Klassert <steffen.klassert@secunet.com>
      Cc: PaX Team <pageexec@freemail.hu>
      Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
      [bwh: Backported to 3.2: adjust context]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      cc058b6f
    • xuejiufei's avatar
      ocfs2/dlm: clear refmap bit of recovery lock while doing local recovery cleanup · ee614e58
      xuejiufei authored
      commit c95a5180 upstream.
      
      When recovery master down, dlm_do_local_recovery_cleanup() only remove
      the $RECOVERY lock owned by dead node, but do not clear the refmap bit.
      Which will make umount thread falling in dead loop migrating $RECOVERY
      to the dead node.
      Signed-off-by: default avatarxuejiufei <xuejiufei@huawei.com>
      Reviewed-by: default avatarJoseph Qi <joseph.qi@huawei.com>
      Cc: Mark Fasheh <mfasheh@suse.de>
      Cc: Joel Becker <jlbec@evilplan.org>
      Cc: Junxiao Bi <junxiao.bi@oracle.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      ee614e58
    • Tetsuo Handa's avatar
      mm, vmstat: fix wrong WQ sleep when memory reclaim doesn't make any progress · 939f1e0d
      Tetsuo Handa authored
      commit 564e81a5 upstream.
      
      Jan Stancek has reported that system occasionally hanging after "oom01"
      testcase from LTP triggers OOM.  Guessing from a result that there is a
      kworker thread doing memory allocation and the values between "Node 0
      Normal free:" and "Node 0 Normal:" differs when hanging, vmstat is not
      up-to-date for some reason.
      
      According to commit 373ccbe5 ("mm, vmstat: allow WQ concurrency to
      discover memory reclaim doesn't make any progress"), it meant to force
      the kworker thread to take a short sleep, but it by error used
      schedule_timeout(1).  We missed that schedule_timeout() in state
      TASK_RUNNING doesn't do anything.
      
      Fix it by using schedule_timeout_uninterruptible(1) which forces the
      kworker thread to take a short sleep in order to make sure that vmstat
      is up-to-date.
      
      Fixes: 373ccbe5 ("mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress")
      Signed-off-by: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
      Reported-by: default avatarJan Stancek <jstancek@redhat.com>
      Acked-by: default avatarMichal Hocko <mhocko@suse.com>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Cristopher Lameter <clameter@sgi.com>
      Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
      Cc: Arkadiusz Miskiewicz <arekm@maven.pl>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      939f1e0d
    • Hannes Reinecke's avatar
      scsi_dh_rdac: always retry MODE SELECT on command lock violation · 075ee9fb
      Hannes Reinecke authored
      commit d2d06d4f upstream.
      
      If MODE SELECT returns with sense '05/91/36' (command lock violation)
      it should always be retried without counting the number of retries.
      During an HBA upgrade or similar circumstances one might see a flood
      of MODE SELECT command from various HBAs, which will easily trigger
      the sense code and exceed the retry count.
      Signed-off-by: default avatarHannes Reinecke <hare@suse.de>
      Reviewed-by: default avatarJohannes Thumshirn <jthumshirn@suse.de>
      Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      075ee9fb
    • Mauro Carvalho Chehab's avatar
      saa7134-alsa: Only frees registered sound cards · 6d08d178
      Mauro Carvalho Chehab authored
      commit ac75fe5d upstream.
      
      That prevents this bug:
      [ 2382.269496] BUG: unable to handle kernel NULL pointer dereference at 0000000000000540
      [ 2382.270013] IP: [<ffffffffa01fe616>] snd_card_free+0x36/0x70 [snd]
      [ 2382.270013] PGD 0
      [ 2382.270013] Oops: 0002 [#1] SMP
      [ 2382.270013] Modules linked in: saa7134_alsa(-) tda1004x saa7134_dvb videobuf2_dvb dvb_core tda827x tda8290 tuner saa7134 tveeprom videobuf2_dma_sg videobuf2_memops videobuf2_v4l2 videobuf2_core v4l2_common videodev media auth_rpcgss nfsv4 dns_resolver nfs lockd grace sunrpc tun bridge stp llc ebtables ip6table_filter ip6_tables nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack it87 hwmon_vid snd_hda_codec_idt snd_hda_codec_generic iTCO_wdt iTCO_vendor_support snd_hda_intel snd_hda_codec snd_hwdep snd_hda_core snd_seq pcspkr i2c_i801 snd_seq_device snd_pcm snd_timer lpc_ich snd mfd_core soundcore binfmt_misc i915 video i2c_algo_bit drm_kms_helper drm r8169 ata_generic serio_raw pata_acpi mii i2c_core [last unloaded: videobuf2_memops]
      [ 2382.270013] CPU: 0 PID: 4899 Comm: rmmod Not tainted 4.5.0-rc1+ #4
      [ 2382.270013] Hardware name: PCCHIPS P17G/P17G, BIOS 080012  05/14/2008
      [ 2382.270013] task: ffff880039c38000 ti: ffff88003c764000 task.ti: ffff88003c764000
      [ 2382.270013] RIP: 0010:[<ffffffffa01fe616>]  [<ffffffffa01fe616>] snd_card_free+0x36/0x70 [snd]
      [ 2382.270013] RSP: 0018:ffff88003c767ea0  EFLAGS: 00010286
      [ 2382.270013] RAX: ffff88003c767eb8 RBX: 0000000000000000 RCX: 0000000000006260
      [ 2382.270013] RDX: ffffffffa020a060 RSI: ffffffffa0206de1 RDI: ffff88003c767eb0
      [ 2382.270013] RBP: ffff88003c767ed8 R08: 0000000000019960 R09: ffffffff811a5412
      [ 2382.270013] R10: ffffea0000d7c200 R11: 0000000000000000 R12: ffff88003c767ea8
      [ 2382.270013] R13: 00007ffe760617f7 R14: 0000000000000000 R15: 0000557625d7f1e0
      [ 2382.270013] FS:  00007f80bb1c0700(0000) GS:ffff88003f400000(0000) knlGS:0000000000000000
      [ 2382.270013] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
      [ 2382.270013] CR2: 0000000000000540 CR3: 000000003c00f000 CR4: 00000000000006f0
      [ 2382.270013] Stack:
      [ 2382.270013]  000000003c767ed8 ffffffff00000000 ffff880000000000 ffff88003c767eb8
      [ 2382.270013]  ffff88003c767eb8 ffffffffa049a890 00007ffe76060060 ffff88003c767ef0
      [ 2382.270013]  ffffffffa049889d ffffffffa049a500 ffff88003c767f48 ffffffff8111079c
      [ 2382.270013] Call Trace:
      [ 2382.270013]  [<ffffffffa049889d>] saa7134_alsa_exit+0x1d/0x780 [saa7134_alsa]
      [ 2382.270013]  [<ffffffff8111079c>] SyS_delete_module+0x19c/0x1f0
      [ 2382.270013]  [<ffffffff8170fc2e>] entry_SYSCALL_64_fastpath+0x12/0x71
      [ 2382.270013] Code: 20 a0 48 c7 c6 e1 6d 20 a0 48 89 e5 41 54 53 4c 8d 65 d0 48 89 fb 48 83 ec 28 c7 45 d0 00 00 00 00 49 8d 7c 24 08 e8 7a 55 ed e0 <4c> 89 a3 40 05 00 00 48 89 df e8 eb fd ff ff 85 c0 75 1a 48 8d
      [ 2382.270013] RIP  [<ffffffffa01fe616>] snd_card_free+0x36/0x70 [snd]
      [ 2382.270013]  RSP <ffff88003c767ea0>
      [ 2382.270013] CR2: 0000000000000540
      Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@osg.samsung.com>
      [bwh: Backported to 3.2: adjust filename]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      6d08d178
    • Takashi Iwai's avatar
      ALSA: timer: Fix leftover link at closing · 98ea665b
      Takashi Iwai authored
      commit 094fd3be upstream.
      
      In ALSA timer core, the active timer instance is managed in
      active_list linked list.  Each element is added / removed dynamically
      at timer start, stop and in timer interrupt.  The problem is that
      snd_timer_interrupt() has a thinko and leaves the element in
      active_list when it's the last opened element.  This eventually leads
      to list corruption or use-after-free error.
      
      This hasn't been revealed because we used to delete the list forcibly
      in snd_timer_stop() in the past.  However, the recent fix avoids the
      double-stop behavior (in commit [f784beb7: ALSA: timer: Fix link
      corruption due to double start or stop]), and this leak hits reality.
      
      This patch fixes the link management in snd_timer_interrupt().  Now it
      simply unlinks no matter which stream is.
      
      BugLink: http://lkml.kernel.org/r/CACT4Y+Yy2aukHP-EDp8-ziNqNNmb-NTf=jDWXMP7jB8HDa2vng@mail.gmail.comReported-by: default avatarDmitry Vyukov <dvyukov@google.com>
      Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      98ea665b
    • Mauro Carvalho Chehab's avatar
      tda1004x: only update the frontend properties if locked · 2fb15bd1
      Mauro Carvalho Chehab authored
      commit e8beb023 upstream.
      
      The tda1004x was updating the properties cache before locking.
      If the device is not locked, the data at the registers are just
      random values with no real meaning.
      
      This caused the driver to fail with libdvbv5, as such library
      calls GET_PROPERTY from time to time, in order to return the
      DVB stats.
      
      Tested with a saa7134 card 78:
      	ASUSTeK P7131 Dual, vendor PCI ID: 1043:4862
      Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@osg.samsung.com>
      [bwh: Backported to 3.2: adjust filename]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      2fb15bd1
    • Mathias Nyman's avatar
      xhci: Fix list corruption in urb dequeue at host removal · 83c42842
      Mathias Nyman authored
      commit 5c821711 upstream.
      
      xhci driver frees data for all devices, both usb2 and and usb3 the
      first time usb_remove_hcd() is called, including td_list and and xhci_ring
      structures.
      
      When usb_remove_hcd() is called a second time for the second xhci bus it
      will try to dequeue all pending urbs, and touches td_list which is already
      freed for that endpoint.
      Reported-by: default avatarJoe Lawrence <joe.lawrence@stratus.com>
      Tested-by: default avatarJoe Lawrence <joe.lawrence@stratus.com>
      Signed-off-by: default avatarMathias Nyman <mathias.nyman@linux.intel.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      83c42842
    • Lu Baolu's avatar
      usb: xhci: apply XHCI_PME_STUCK_QUIRK to Intel Broxton-M platforms · 89031706
      Lu Baolu authored
      commit ccc04afb upstream.
      
      Intel Broxton M was verifed to require XHCI_PME_STUCK_QUIRK quirk as well.
      Signed-off-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
      Signed-off-by: default avatarMathias Nyman <mathias.nyman@linux.intel.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      89031706
    • Mathias Nyman's avatar
      Revert "xhci: don't finish a TD if we get a short-transfer event mid TD" · d3444681
      Mathias Nyman authored
      commit a6835090 upstream.
      
      This reverts commit e210c422 ("xhci: don't finish a TD if we get a
      short transfer event mid TD")
      
      Turns out that most host controllers do not follow the xHCI specs and never
      send the second event for the last TRB in the TD if there was a short event
      mid-TD.
      
      Returning the URB directly after the first short-transfer event is far
      better than never returning the URB. (class drivers usually timeout
      after 30sec). For the hosts that do send the second event we will go
      back to treating it as misplaced event and print an error message for it.
      
      The origial patch was sent to stable kernels and needs to be reverted from
      there as well
      Signed-off-by: default avatarMathias Nyman <mathias.nyman@linux.intel.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      [bwh: Backported to 3.2: adjust context]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      d3444681
    • Takashi Iwai's avatar
      ALSA: seq: Fix lockdep warnings due to double mutex locks · 96c6b772
      Takashi Iwai authored
      commit 7f0973e9 upstream.
      
      The port subscription code uses double mutex locks for source and
      destination ports, and this may become racy once when wrongly set up.
      It leads to lockdep warning splat, typically triggered by fuzzer like
      syzkaller, although the actual deadlock hasn't been seen, so far.
      
      This patch simplifies the handling by reducing to two single locks, so
      that no lockdep warning will be trigger any longer.
      
      By splitting to two actions, a still-in-progress element shall be
      added in one list while handling another.  For ignoring this element,
      a new check is added in deliver_to_subscribers().
      
      Along with it, the code to add/remove the subscribers list element was
      cleaned up and refactored.
      
      BugLink: http://lkml.kernel.org/r/CACT4Y+aKQXV7xkBW9hpQbzaDO7LrUvohxWh-UwMxXjDy-yBD=A@mail.gmail.comReported-by: default avatarDmitry Vyukov <dvyukov@google.com>
      Tested-by: default avatarDmitry Vyukov <dvyukov@google.com>
      Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      96c6b772
    • Takashi Iwai's avatar
      ALSA: rawmidi: Fix race at copying & updating the position · a0e3501f
      Takashi Iwai authored
      commit 81f57754 upstream.
      
      The rawmidi read and write functions manage runtime stream status
      such as runtime->appl_ptr and runtime->avail.  These point where to
      copy the new data and how many bytes have been copied (or to be
      read).  The problem is that rawmidi read/write call copy_from_user()
      or copy_to_user(), and the runtime spinlock is temporarily unlocked
      and relocked while copying user-space.  Since the current code
      advances and updates the runtime status after the spin unlock/relock,
      the copy and the update may be asynchronous, and eventually
      runtime->avail might go to a negative value when many concurrent
      accesses are done.  This may lead to memory corruption in the end.
      
      For fixing this race, in this patch, the status update code is
      performed in the same lock before the temporary unlock.  Also, the
      spinlock is now taken more widely in snd_rawmidi_kernel_read1() for
      protecting more properly during the whole operation.
      
      BugLink: http://lkml.kernel.org/r/CACT4Y+b-dCmNf1GpgPKfDO0ih+uZCL2JV4__j-r1kdhPLSgQCQ@mail.gmail.comReported-by: default avatarDmitry Vyukov <dvyukov@google.com>
      Tested-by: default avatarDmitry Vyukov <dvyukov@google.com>
      Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      a0e3501f
    • Takashi Iwai's avatar
      ALSA: rawmidi: Make snd_rawmidi_transmit() race-free · b6d58474
      Takashi Iwai authored
      commit 06ab3003 upstream.
      
      A kernel WARNING in snd_rawmidi_transmit_ack() is triggered by
      syzkaller fuzzer:
        WARNING: CPU: 1 PID: 20739 at sound/core/rawmidi.c:1136
      Call Trace:
       [<     inline     >] __dump_stack lib/dump_stack.c:15
       [<ffffffff82999e2d>] dump_stack+0x6f/0xa2 lib/dump_stack.c:50
       [<ffffffff81352089>] warn_slowpath_common+0xd9/0x140 kernel/panic.c:482
       [<ffffffff813522b9>] warn_slowpath_null+0x29/0x30 kernel/panic.c:515
       [<ffffffff84f80bd5>] snd_rawmidi_transmit_ack+0x275/0x400 sound/core/rawmidi.c:1136
       [<ffffffff84fdb3c1>] snd_virmidi_output_trigger+0x4b1/0x5a0 sound/core/seq/seq_virmidi.c:163
       [<     inline     >] snd_rawmidi_output_trigger sound/core/rawmidi.c:150
       [<ffffffff84f87ed9>] snd_rawmidi_kernel_write1+0x549/0x780 sound/core/rawmidi.c:1223
       [<ffffffff84f89fd3>] snd_rawmidi_write+0x543/0xb30 sound/core/rawmidi.c:1273
       [<ffffffff817b0323>] __vfs_write+0x113/0x480 fs/read_write.c:528
       [<ffffffff817b1db7>] vfs_write+0x167/0x4a0 fs/read_write.c:577
       [<     inline     >] SYSC_write fs/read_write.c:624
       [<ffffffff817b50a1>] SyS_write+0x111/0x220 fs/read_write.c:616
       [<ffffffff86336c36>] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185
      
      Also a similar warning is found but in another path:
      Call Trace:
       [<     inline     >] __dump_stack lib/dump_stack.c:15
       [<ffffffff82be2c0d>] dump_stack+0x6f/0xa2 lib/dump_stack.c:50
       [<ffffffff81355139>] warn_slowpath_common+0xd9/0x140 kernel/panic.c:482
       [<ffffffff81355369>] warn_slowpath_null+0x29/0x30 kernel/panic.c:515
       [<ffffffff8527e69a>] rawmidi_transmit_ack+0x24a/0x3b0 sound/core/rawmidi.c:1133
       [<ffffffff8527e851>] snd_rawmidi_transmit_ack+0x51/0x80 sound/core/rawmidi.c:1163
       [<ffffffff852d9046>] snd_virmidi_output_trigger+0x2b6/0x570 sound/core/seq/seq_virmidi.c:185
       [<     inline     >] snd_rawmidi_output_trigger sound/core/rawmidi.c:150
       [<ffffffff85285a0b>] snd_rawmidi_kernel_write1+0x4bb/0x760 sound/core/rawmidi.c:1252
       [<ffffffff85287b73>] snd_rawmidi_write+0x543/0xb30 sound/core/rawmidi.c:1302
       [<ffffffff817ba5f3>] __vfs_write+0x113/0x480 fs/read_write.c:528
       [<ffffffff817bc087>] vfs_write+0x167/0x4a0 fs/read_write.c:577
       [<     inline     >] SYSC_write fs/read_write.c:624
       [<ffffffff817bf371>] SyS_write+0x111/0x220 fs/read_write.c:616
       [<ffffffff86660276>] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185
      
      In the former case, the reason is that virmidi has an open code
      calling snd_rawmidi_transmit_ack() with the value calculated outside
      the spinlock.   We may use snd_rawmidi_transmit() in a loop just for
      consuming the input data, but even there, there is a race between
      snd_rawmidi_transmit_peek() and snd_rawmidi_tranmit_ack().
      
      Similarly in the latter case, it calls snd_rawmidi_transmit_peek() and
      snd_rawmidi_tranmit_ack() separately without protection, so they are
      racy as well.
      
      The patch tries to address these issues by the following ways:
      - Introduce the unlocked versions of snd_rawmidi_transmit_peek() and
        snd_rawmidi_transmit_ack() to be called inside the explicit lock.
      - Rewrite snd_rawmidi_transmit() to be race-free (the former case).
      - Make the split calls (the latter case) protected in the rawmidi spin
        lock.
      
      BugLink: http://lkml.kernel.org/r/CACT4Y+YPq1+cYLkadwjWa5XjzF1_Vki1eHnVn-Lm0hzhSpu5PA@mail.gmail.com
      BugLink: http://lkml.kernel.org/r/CACT4Y+acG4iyphdOZx47Nyq_VHGbpJQK-6xNpiqUjaZYqsXOGw@mail.gmail.comReported-by: default avatarDmitry Vyukov <dvyukov@google.com>
      Tested-by: default avatarDmitry Vyukov <dvyukov@google.com>
      Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
      [bwh: Backported to 3.2: adjust context]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      b6d58474