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  1. 20 Aug, 2022 7 commits
    • Peter Xu's avatar
      mm/uffd: reset write protection when unregister with wp-mode · f369b07c
      Peter Xu authored 
      The motivation of this patch comes from a recent report and patchfix from
David Hildenbrand on hugetlb shared handling of wr-protected page [1].

With the reproducer provided in commit message of [1], one can leverage
the uffd-wp lazy-reset of ptes to trigger a hugetlb issue which can affect
not only the attacker process, but also the whole system.

The lazy-reset mechanism of uffd-wp was used to make unregister faster,
meanwhile it has an assumption that any leftover pgtable entries should
only affect the process on its own, so not only the user should be aware
of anything it does, but also it should not affect outside of the process.

But it seems that this is not true, and it can also be utilized to make
some exploit easier.

So far there's no clue showing that the lazy-reset is important to any
userfaultfd users because normally the unregister will only happen once
for a specific range of memory of the lifecycle of the process.

Considering all above, what this patch proposes is to do explicit pte
resets when unregister an uffd region with wr-protect mode enabled.

It should be the same as calling ioctl(UFFDIO_WRITEPROTECT, wp=false)
right before ioctl(UFFDIO_UNREGISTER) for the user.  So potentially it'll
make the unregister slower.  From that pov it's a very slight abi change,
but hopefully nothing should break with this change either.

Regarding to the change itself - core of uffd write [un]protect operation
is moved into a separate function (uffd_wp_range()) and it is reused in
the unregister code path.

Note that the new function will not check for anything, e.g.  ranges or
memory types, because they should have been checked during the previous
UFFDIO_REGISTER or it should have failed already.  It also doesn't check
mmap_changing because we're with mmap write lock held anyway.

I added a Fixes upon introducing of uffd-wp shmem+hugetlbfs because that's
the only issue reported so far and that's the commit David's reproducer
will start working (v5.19+).  But the whole idea actually applies to not
only file memories but also anonymous.  It's just that we don't need to
fix anonymous prior to v5.19- because there's no known way to exploit.

IOW, this patch can also fix the issue reported in [1] as the patch 2 does.

[1] https://lore.kernel.org/all/20220811103435.188481-3-david@redhat.com/

Link: https://lkml.kernel.org/r/20220811201340.39342-1-peterx@redhat.com
Fixes: b1f9e876 ("mm/uffd: enable write protection for shmem & hugetlbfs")
Signed-off-by: default avatarPeter Xu <peterx@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      f369b07c
    • Peter Xu's avatar
      mm/smaps: don't access young/dirty bit if pte unpresent · efd41493
      Peter Xu authored 
      These bits should only be valid when the ptes are present.  Introducing
two booleans for it and set it to false when !pte_present() for both pte
and pmd accountings.

The bug is found during code reading and no real world issue reported, but
logically such an error can cause incorrect readings for either smaps or
smaps_rollup output on quite a few fields.

For example, it could cause over-estimate on values like Shared_Dirty,
Private_Dirty, Referenced.  Or it could also cause under-estimate on
values like LazyFree, Shared_Clean, Private_Clean.

Link: https://lkml.kernel.org/r/20220805160003.58929-1-peterx@redhat.com
Fixes: b1d4d9e0 ("proc/smaps: carefully handle migration entries")
Fixes: c94b6923 ("/proc/PID/smaps: Add PMD migration entry parsing")
Signed-off-by: default avatarPeter Xu <peterx@redhat.com>
Reviewed-by: default avatarVlastimil Babka <vbabka@suse.cz>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarYang Shi <shy828301@gmail.com>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Huang Ying <ying.huang@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      efd41493
    • Hao Lee's avatar
      mm: add DEVICE_ZONE to FOR_ALL_ZONES · a39c5d3c
      Hao Lee authored 
      FOR_ALL_ZONES should be consistent with enum zone_type.  Otherwise,
__count_zid_vm_events have the potential to add count to wrong item when
zid is ZONE_DEVICE.

Link: https://lkml.kernel.org/r/20220807154442.GA18167@haolee.ioSigned-off-by: default avatarHao Lee <haolee.swjtu@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      a39c5d3c
    • Randy Dunlap's avatar
      kernel/sys_ni: add compat entry for fadvise64_64 · a8faed3a
      Randy Dunlap authored 
      When CONFIG_ADVISE_SYSCALLS is not set/enabled and CONFIG_COMPAT is
set/enabled, the riscv compat_syscall_table references
'compat_sys_fadvise64_64', which is not defined:

riscv64-linux-ld: arch/riscv/kernel/compat_syscall_table.o:(.rodata+0x6f8):
undefined reference to `compat_sys_fadvise64_64'

Add 'fadvise64_64' to kernel/sys_ni.c as a conditional COMPAT function so
that when CONFIG_ADVISE_SYSCALLS is not set, there is a fallback function
available.

Link: https://lkml.kernel.org/r/20220807220934.5689-1-rdunlap@infradead.org
Fixes: d3ac21ca ("mm: Support compiling out madvise and fadvise")
Signed-off-by: default avatarRandy Dunlap <rdunlap@infradead.org>
Suggested-by: default avatarArnd Bergmann <arnd@arndb.de>
Reviewed-by: default avatarArnd Bergmann <arnd@arndb.de>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      a8faed3a
    • David Hildenbrand's avatar
      mm/gup: fix FOLL_FORCE COW security issue and remove FOLL_COW · 5535be30
      David Hildenbrand authored 
      Ever since the Dirty COW (CVE-2016-5195) security issue happened, we know
that FOLL_FORCE can be possibly dangerous, especially if there are races
that can be exploited by user space.

Right now, it would be sufficient to have some code that sets a PTE of a
R/O-mapped shared page dirty, in order for it to erroneously become
writable by FOLL_FORCE.  The implications of setting a write-protected PTE
dirty might not be immediately obvious to everyone.

And in fact ever since commit 9ae0f87d ("mm/shmem: unconditionally set
pte dirty in mfill_atomic_install_pte"), we can use UFFDIO_CONTINUE to map
a shmem page R/O while marking the pte dirty.  This can be used by
unprivileged user space to modify tmpfs/shmem file content even if the
user does not have write permissions to the file, and to bypass memfd
write sealing -- Dirty COW restricted to tmpfs/shmem (CVE-2022-2590).

To fix such security issues for good, the insight is that we really only
need that fancy retry logic (FOLL_COW) for COW mappings that are not
writable (!VM_WRITE).  And in a COW mapping, we really only broke COW if
we have an exclusive anonymous page mapped.  If we have something else
mapped, or the mapped anonymous page might be shared (!PageAnonExclusive),
we have to trigger a write fault to break COW.  If we don't find an
exclusive anonymous page when we retry, we have to trigger COW breaking
once again because something intervened.

Let's move away from this mandatory-retry + dirty handling and rely on our
PageAnonExclusive() flag for making a similar decision, to use the same
COW logic as in other kernel parts here as well.  In case we stumble over
a PTE in a COW mapping that does not map an exclusive anonymous page, COW
was not properly broken and we have to trigger a fake write-fault to break
COW.

Just like we do in can_change_pte_writable() added via commit 64fe24a3
("mm/mprotect: try avoiding write faults for exclusive anonymous pages
when changing protection") and commit 76aefad6 ("mm/mprotect: fix
soft-dirty check in can_change_pte_writable()"), take care of softdirty
and uffd-wp manually.

For example, a write() via /proc/self/mem to a uffd-wp-protected range has
to fail instead of silently granting write access and bypassing the
userspace fault handler.  Note that FOLL_FORCE is not only used for debug
access, but also triggered by applications without debug intentions, for
example, when pinning pages via RDMA.

This fixes CVE-2022-2590. Note that only x86_64 and aarch64 are
affected, because only those support CONFIG_HAVE_ARCH_USERFAULTFD_MINOR.

Fortunately, FOLL_COW is no longer required to handle FOLL_FORCE. So
let's just get rid of it.

Thanks to Nadav Amit for pointing out that the pte_dirty() check in
FOLL_FORCE code is problematic and might be exploitable.

Note 1: We don't check for the PTE being dirty because it doesn't matter
	for making a "was COWed" decision anymore, and whoever modifies the
	page has to set the page dirty either way.

Note 2: Kernels before extended uffd-wp support and before
	PageAnonExclusive (< 5.19) can simply revert the problematic
	commit instead and be safe regarding UFFDIO_CONTINUE. A backport to
	v5.19 requires minor adjustments due to lack of
	vma_soft_dirty_enabled().

Link: https://lkml.kernel.org/r/20220809205640.70916-1-david@redhat.com
Fixes: 9ae0f87d ("mm/shmem: unconditionally set pte dirty in mfill_atomic_install_pte")
Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: <stable@vger.kernel.org>	[5.16]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      5535be30
    • Jiri Slaby's avatar
      Revert "zram: remove double compression logic" · 37887783
      Jiri Slaby authored 
      This reverts commit e7be8d1d ("zram: remove double compression
logic") as it causes zram failures.  It does not revert cleanly, PTR_ERR
handling was introduced in the meantime.  This is handled by appropriate
IS_ERR.

When under memory pressure, zs_malloc() can fail.  Before the above
commit, the allocation was retried with direct reclaim enabled (GFP_NOIO).
After the commit, it is not -- only __GFP_KSWAPD_RECLAIM is tried.

So when the failure occurs under memory pressure, the overlaying
filesystem such as ext2 (mounted by ext4 module in this case) can emit
failures, making the (file)system unusable:
  EXT4-fs warning (device zram0): ext4_end_bio:343: I/O error 10 writing to inode 16386 starting block 159744)
  Buffer I/O error on device zram0, logical block 159744

With direct reclaim, memory is really reclaimed and allocation succeeds,
eventually.  In the worst case, the oom killer is invoked, which is proper
outcome if user sets up zram too large (in comparison to available RAM).

This very diff doesn't apply to 5.19 (stable) cleanly (see PTR_ERR note
above). Use revert of e7be8d1d directly.

Link: https://bugzilla.suse.com/show_bug.cgi?id=1202203
Link: https://lkml.kernel.org/r/20220810070609.14402-1-jslaby@suse.cz
Fixes: e7be8d1d ("zram: remove double compression logic")
Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
Reviewed-by: default avatarSergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Alexey Romanov <avromanov@sberdevices.ru>
Cc: Dmitry Rokosov <ddrokosov@sberdevices.ru>
Cc: Lukas Czerner <lczerner@redhat.com>
Cc: <stable@vger.kernel.org>	[5.19]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      37887783
    • Dan Carpenter's avatar
      get_maintainer: add Alan to .get_maintainer.ignore · d10a72de
      Dan Carpenter authored 
      Alan asked to be added to the .get_maintainer.ignore list.

Link: https://lkml.kernel.org/r/YvN30KhO9aD5Sza9@kiliSigned-off-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      d10a72de
  3. 14 Aug, 2022 10 commits
    • Linus Torvalds's avatar
      Linux 6.0-rc1 · 568035b0
      Linus Torvalds authored
      568035b0
    • Yury Norov's avatar
      radix-tree: replace gfp.h inclusion with gfp_types.h · 9f162193
      Yury Norov authored 
      Radix tree header includes gfp.h for __GFP_BITS_SHIFT only. Now we
have gfp_types.h for this.

Fixes powerpc allmodconfig build:

   In file included from include/linux/nodemask.h:97,
                    from include/linux/mmzone.h:17,
                    from include/linux/gfp.h:7,
                    from include/linux/radix-tree.h:12,
                    from include/linux/idr.h:15,
                    from include/linux/kernfs.h:12,
                    from include/linux/sysfs.h:16,
                    from include/linux/kobject.h:20,
                    from include/linux/pci.h:35,
                    from arch/powerpc/kernel/prom_init.c:24:
   include/linux/random.h: In function 'add_latent_entropy':
>> include/linux/random.h:25:46: error: 'latent_entropy' undeclared (first use in this function); did you mean 'add_latent_entropy'?
      25 |         add_device_randomness((const void *)&latent_entropy, sizeof(latent_entropy));
         |                                              ^~~~~~~~~~~~~~
         |                                              add_latent_entropy
   include/linux/random.h:25:46: note: each undeclared identifier is reported only once for each function it appears in
Reported-by: default avatarkernel test robot <lkp@intel.com>
CC: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: default avatarYury Norov <yury.norov@gmail.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      9f162193
    • Linus Torvalds's avatar
      Merge tag 'pull-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs · 74cbb480
      Linus Torvalds authored 
      Pull vfs lseek fix from Al Viro:
 "Fix proc_reg_llseek() breakage. Always had been possible if somebody
  left NULL ->proc_lseek, became a practical issue now"

* tag 'pull-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  take care to handle NULL ->proc_lseek()
      74cbb480
    • Al Viro's avatar
      take care to handle NULL ->proc_lseek() · 3f61631d
      Al Viro authored 
      Easily done now, just by clearing FMODE_LSEEK in ->f_mode
during proc_reg_open() for such entries.

Fixes: 868941b1 "fs: remove no_llseek"
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      3f61631d
    • Linus Torvalds's avatar
      Merge tag 'for-linus-6.0-rc1b-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip · 5d6a0f4d
      Linus Torvalds authored 
      Pull more xen updates from Juergen Gross:

 - fix the handling of the "persistent grants" feature negotiation
   between Xen blkfront and Xen blkback drivers

 - a cleanup of xen.config and adding xen.config to Xen section in
   MAINTAINERS

 - support HVMOP_set_evtchn_upcall_vector, which is more compliant to
   "normal" interrupt handling than the global callback used up to now

 - further small cleanups

* tag 'for-linus-6.0-rc1b-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  MAINTAINERS: add xen config fragments to XEN HYPERVISOR sections
  xen: remove XEN_SCRUB_PAGES in xen.config
  xen/pciback: Fix comment typo
  xen/xenbus: fix return type in xenbus_file_read()
  xen-blkfront: Apply 'feature_persistent' parameter when connect
  xen-blkback: Apply 'feature_persistent' parameter when connect
  xen-blkback: fix persistent grants negotiation
  x86/xen: Add support for HVMOP_set_evtchn_upcall_vector
      5d6a0f4d
    • Linus Torvalds's avatar
      Merge tag 'perf-tools-fixes-for-v6.0-2022-08-13' of... · 96f86ff0
      Linus Torvalds authored 
      Merge tag 'perf-tools-fixes-for-v6.0-2022-08-13' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux

Pull more perf tool updates from Arnaldo Carvalho de Melo:

 - 'perf c2c' now supports ARM64, adjust its output to cope with
   differences with what is in x86_64. Now go find false sharing on
   ARM64 (at least Neoverse) as well!

 - Refactor the JSON processing, making the output more compact and thus
   reducing the size of the resulting perf binary

 - Improvements for 'perf offcpu' profiling, including tracking child
   processes

 - Update Intel JSON metrics and events files for broadwellde,
   broadwellx, cascadelakex, haswellx, icelakex, ivytown, jaketown,
   knightslanding, sapphirerapids, skylakex and snowridgex

 - Add 'perf stat' JSON output and a 'perf test' entry for it

 - Ignore memfd and anonymous mmap events if jitdump present

 - Refactor 'perf test' shell tests allowing subdirs

 - Fix an error handling path in 'parse_perf_probe_command()'

 - Fixes for the guest Intel PT tracing patchkit in the 1st batch of
   this merge window

 - Print debuginfod queries if -v option is used, to explain delays in
   processing when debuginfo servers are enabled to fetch DSOs with
   richer symbol tables

 - Improve error message for 'perf record -p not_existing_pid'

 - Fix openssl and libbpf feature detection

 - Add PMU pai_crypto event description for IBM z16 on 'perf list'

 - Fix typos and duplicated words on comments in various places

* tag 'perf-tools-fixes-for-v6.0-2022-08-13' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux: (81 commits)
  perf test: Refactor shell tests allowing subdirs
  perf vendor events: Update events for snowridgex
  perf vendor events: Update events and metrics for skylakex
  perf vendor events: Update metrics for sapphirerapids
  perf vendor events: Update events for knightslanding
  perf vendor events: Update metrics for jaketown
  perf vendor events: Update metrics for ivytown
  perf vendor events: Update events and metrics for icelakex
  perf vendor events: Update events and metrics for haswellx
  perf vendor events: Update events and metrics for cascadelakex
  perf vendor events: Update events and metrics for broadwellx
  perf vendor events: Update metrics for broadwellde
  perf jevents: Fold strings optimization
  perf jevents: Compress the pmu_events_table
  perf metrics: Copy entire pmu_event in find metric
  perf pmu-events: Hide the pmu_events
  perf pmu-events: Don't assume pmu_event is an array
  perf pmu-events: Move test events/metrics to JSON
  perf test: Use full metric resolution
  perf pmu-events: Hide pmu_events_map
  ...
      96f86ff0
    • Linus Torvalds's avatar
      Merge tag 'powerpc-6.0-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux · d785610f
      Linus Torvalds authored 
      Pull powerpc fixes from Michael Ellerman:

 - Ensure we never emit lwarx with EH=1 on 32-bit, because some 32-bit
   CPUs trap on it rather than ignoring it as they should.

 - Fix ftrace when building with clang, which was broken by some
   refactoring.

 - A couple of other minor fixes.

Thanks to Christophe Leroy, Naveen N.  Rao, Nick Desaulniers, Ondrej
Mosnacek, Pali Rohár, Russell Currey, and Segher Boessenkool.

* tag 'powerpc-6.0-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/kexec: Fix build failure from uninitialised variable
  powerpc/ppc-opcode: Fix PPC_RAW_TW()
  powerpc64/ftrace: Fix ftrace for clang builds
  powerpc: Make eh value more explicit when using lwarx
  powerpc: Don't hide eh field of lwarx behind a macro
  powerpc: Fix eh field when calling lwarx on PPC32
      d785610f
    • Linus Torvalds's avatar
      Merge tag 'pull-work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs · aea23e7c
      Linus Torvalds authored 
      Pull /proc/mounts fix from Al Viro:
 "Fix for /proc/mounts escaping - escape the '#' character too"

* tag 'pull-work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  vfs: escape hash as well
      aea23e7c
    • Linus Torvalds's avatar
      Merge tag '5.20-rc-smb3-client-fixes-part2' of git://git.samba.org/sfrench/cifs-2.6 · 332019e2
      Linus Torvalds authored 
      Pull more cifs updates from Steve French:

 - two fixes for stable, one for a lock length miscalculation, and
   another fixes a lease break timeout bug

 - improvement to handle leases, allows the close timeout to be
   configured more safely

 - five restructuring/cleanup patches

* tag '5.20-rc-smb3-client-fixes-part2' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: Do not access tcon->cfids->cfid directly from is_path_accessible
  cifs: Add constructor/destructors for tcon->cfid
  SMB3: fix lease break timeout when multiple deferred close handles for the same file.
  smb3: allow deferred close timeout to be configurable
  cifs: Do not use tcon->cfid directly, use the cfid we get from open_cached_dir
  cifs: Move cached-dir functions into a separate file
  cifs: Remove {cifs,nfs}_fscache_release_page()
  cifs: fix lock length calculation
      332019e2
    • David Howells's avatar
      afs: Enable multipage folio support · 8549a263
      David Howells authored 
      Enable multipage folio support for the afs filesystem.

Support has already been implemented in netfslib, fscache and cachefiles
and in most of afs, but I've waited for Matthew Wilcox's latest folio
changes.

Note that it does require a change to afs_write_begin() to return the
correct subpage.  This is a "temporary" change as we're working on
getting rid of the need for ->write_begin() and ->write_end()
completely, at least as far as network filesystems are concerned - but
it doesn't prevent afs from making use of the capability.
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Acked-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Tested-by: kafs-testing@auristor.com
Cc: Marc Dionne <marc.dionne@auristor.com>
Cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/lkml/2274528.1645833226@warthog.procyon.org.uk/Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      8549a263
  5. 13 Aug, 2022 23 commits
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