- 21 Dec, 2018 3 commits
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Davidlohr Bueso authored
[ Upstream commit 223f8911 ] Allows for more flexible debugging. Link: http://lkml.kernel.org/r/20170719014603.19029-5-dave@stgolabs.netSigned-off-by:
Davidlohr Bueso <dbueso@suse.de> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by:
Sasha Levin <sashal@kernel.org>
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Davidlohr Bueso authored
[ Upstream commit c46ecce4 ] ... such that a user can specify visiting all the nodes in the tree (intersects with the world). This is a nice opposite from the very basic default query which is a single point. Link: http://lkml.kernel.org/r/20170518174936.20265-5-dave@stgolabs.netSigned-off-by:
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Davidlohr Bueso authored
[ Upstream commit a54dae03 ] Allows for more flexible debugging. Link: http://lkml.kernel.org/r/20170518174936.20265-3-dave@stgolabs.netSigned-off-by:
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- 17 Dec, 2018 37 commits
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Greg Kroah-Hartman authored
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Shuah Khan authored
commit 3d2c86e3 upstream. Remove networking from Documentation Makefile to move the test to selftests. Update networking/timestamping Makefile to work under selftests. These tests will not be run as part of selftests suite and will not be included in install targets. They can be built and run separately for now. This is part of the effort to move runnable code from Documentation. Acked-by:
Jonathan Corbet <corbet@lwn.net> Signed-off-by:
Shuah Khan <shuahkh@osg.samsung.com> [ added to 4.4.y stable to remove a build warning - gregkh] Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Arnd Bergmann authored
commit 6098d7dd upstream. Inlining these functions creates lots of stack variables that each take 64 bytes when KASAN is enabled, leading to this warning about potential stack overflow: drivers/net/ethernet/rocker/rocker_ofdpa.c: In function 'ofdpa_cmd_flow_tbl_add': drivers/net/ethernet/rocker/rocker_ofdpa.c:621:1: error: the frame size of 2752 bytes is larger than 1536 bytes [-Werror=frame-larger-than=] gcc-8 can now consolidate the stack slots itself, but on older versions we get the same behavior by using a temporary variable that holds a copy of the inline function argument. Cc: stable@vger.kernel.org Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715Signed-off-by:
Arnd Bergmann <arnd@arndb.de> Signed-off-by:
David S. Miller <davem@davemloft.net> Signed-off-by:
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Guenter Roeck authored
commit fd29edc7 upstream. gcc 8.1.0 generates the following warnings. drivers/staging/speakup/kobjects.c: In function 'punc_store': drivers/staging/speakup/kobjects.c:522:2: warning: 'strncpy' output truncated before terminating nul copying as many bytes from a string as its length drivers/staging/speakup/kobjects.c:504:6: note: length computed here drivers/staging/speakup/kobjects.c: In function 'synth_store': drivers/staging/speakup/kobjects.c:391:2: warning: 'strncpy' output truncated before terminating nul copying as many bytes from a string as its length drivers/staging/speakup/kobjects.c:388:8: note: length computed here Using strncpy() is indeed less than perfect since the length of data to be copied has already been determined with strlen(). Replace strncpy() with memcpy() to address the warning and optimize the code a little. Signed-off-by:
Guenter Roeck <linux@roeck-us.net> Reviewed-by:
Samuel Thibault <samuel.thibault@ens-lyon.org> Signed-off-by:
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Sudip Mukherjee authored
commit 59921b23 upstream. hw->DACreg has a size of 80 bytes and MGADACbpp32 has 21. So when memcpy copies MGADACbpp32 to hw->DACreg it copies 80 bytes but only 21 bytes are valid. Signed-off-by:
Sudip Mukherjee <sudip.mukherjee@codethink.co.uk> Signed-off-by:
Tomi Valkeinen <tomi.valkeinen@ti.com> Signed-off-by:
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Arnd Bergmann authored
commit 3cd890db upstream. A typical code fragment was copied across many dvb-frontend drivers and causes large stack frames when built with with CONFIG_KASAN on gcc-5/6/7: drivers/media/dvb-frontends/cxd2841er.c:3225:1: error: the frame size of 3992 bytes is larger than 3072 bytes [-Werror=frame-larger-than=] drivers/media/dvb-frontends/cxd2841er.c:3404:1: error: the frame size of 3136 bytes is larger than 3072 bytes [-Werror=frame-larger-than=] drivers/media/dvb-frontends/stv0367.c:3143:1: error: the frame size of 4016 bytes is larger than 3072 bytes [-Werror=frame-larger-than=] drivers/media/dvb-frontends/stv090x.c:3430:1: error: the frame size of 5312 bytes is larger than 3072 bytes [-Werror=frame-larger-than=] drivers/media/dvb-frontends/stv090x.c:4248:1: error: the frame size of 4872 bytes is larger than 3072 bytes [-Werror=frame-larger-than=] gcc-8 now solves this by consolidating the stack slots for the argument variables, but on older compilers we can get the same behavior by taking the pointer of a local variable rather than the inline function argument. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715 Cc: stable@vger.kernel.org Signed-off-by:
Mauro Carvalho Chehab <mchehab@s-opensource.com> Signed-off-by:
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Willy Tarreau authored
commit 7f7ccc2c upstream. proc_pid_cmdline_read() and environ_read() directly access the target process' VM to retrieve the command line and environment. If this process remaps these areas onto a file via mmap(), the requesting process may experience various issues such as extra delays if the underlying device is slow to respond. Let's simply refuse to access file-backed areas in these functions. For this we add a new FOLL_ANON gup flag that is passed to all calls to access_remote_vm(). The code already takes care of such failures (including unmapped areas). Accesses via /proc/pid/mem were not changed though. This was assigned CVE-2018-1120. Note for stable backports: the patch may apply to kernels prior to 4.11 but silently miss one location; it must be checked that no call to access_remote_vm() keeps zero as the last argument. Reported-by:
Qualys Security Advisory <qsa@qualys.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by:
Willy Tarreau <w@1wt.eu> Signed-off-by:
Ben Hutchings <ben.hutchings@codethink.co.uk> Signed-off-by:
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Linus Torvalds authored
commit 272ddc8b upstream. Now that Lorenzo cleaned things up and made the FOLL_FORCE users explicit, it becomes obvious how some of them don't really need FOLL_FORCE at all. So remove FOLL_FORCE from the proc code that reads the command line and arguments from user space. The mem_rw() function actually does want FOLL_FORCE, because gdd (and possibly many other debuggers) use it as a much more convenient version of PTRACE_PEEKDATA, but we should consider making the FOLL_FORCE part conditional on actually being a ptracer. This does not actually do that, just moves adds a comment to that effect and moves the gup_flags settings next to each other. Signed-off-by:
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Lorenzo Stoakes authored
commit 6347e8d5 upstream. This removes the 'write' argument from access_remote_vm() and replaces it with 'gup_flags' as use of this function previously silently implied FOLL_FORCE, whereas after this patch callers explicitly pass this flag. We make this explicit as use of FOLL_FORCE can result in surprising behaviour (and hence bugs) within the mm subsystem. Signed-off-by:
Lorenzo Stoakes <lstoakes@gmail.com> Acked-by:
Michal Hocko <mhocko@suse.com> Signed-off-by:
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Lorenzo Stoakes authored
commit 442486ec upstream. This removes the 'write' argument from __access_remote_vm() and replaces it with 'gup_flags' as use of this function previously silently implied FOLL_FORCE, whereas after this patch callers explicitly pass this flag. We make this explicit as use of FOLL_FORCE can result in surprising behaviour (and hence bugs) within the mm subsystem. Signed-off-by:
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Lorenzo Stoakes authored
commit 768ae309 upstream. This removes the 'write' and 'force' from get_user_pages() and replaces them with 'gup_flags' to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem. Signed-off-by:
Christian König <christian.koenig@amd.com> Acked-by:
Jesper Nilsson <jesper.nilsson@axis.com> Acked-by:
Jan Kara <jack@suse.cz> Signed-off-by:
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Lorenzo Stoakes authored
commit 7f23b350 upstream. This removes the 'write' and 'force' from get_vaddr_frames() and replaces them with 'gup_flags' to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem. Signed-off-by:
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Lorenzo Stoakes authored
commit 3b913179 upstream. This removes the 'write' and 'force' use from get_user_pages_locked() and replaces them with 'gup_flags' to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem. Signed-off-by:
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Lorenzo Stoakes authored
commit c164154f upstream. This removes the 'write' and 'force' use from get_user_pages_unlocked() and replaces them with 'gup_flags' to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem. Signed-off-by:
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Ben Hutchings authored
Extracted from commit cde70140 "mm/gup: Overload get_user_pages() functions". This is needed before picking commit 768ae309 "mm: replace get_user_pages() write/force parameters with gup_flags". Signed-off-by:
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Lorenzo Stoakes authored
commit d4944b0e upstream. This removes the redundant 'write' and 'force' parameters from __get_user_pages_unlocked() to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem. Signed-off-by:
Paolo Bonzini <pbonzini@redhat.com> Reviewed-by:
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Lorenzo Stoakes authored
commit 859110d7 upstream. This removes the redundant 'write' and 'force' parameters from __get_user_pages_locked() to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem. Signed-off-by:
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Jens Axboe authored
commit f7068114 upstream. We're casting the CDROM layer request_sense to the SCSI sense buffer, but the former is 64 bytes and the latter is 96 bytes. As we generally allocate these on the stack, we end up blowing up the stack. Fix this by wrapping the scsi_execute() call with a properly sized sense buffer, and copying back the bits for the CDROM layer. Reported-by:
Piotr Gabriel Kosinski <pg.kosinski@gmail.com> Reported-by:
Daniel Shapira <daniel@twistlock.com> Tested-by:
Kees Cook <keescook@chromium.org> Fixes: 82ed4db4 ("block: split scsi_request out of struct request") Signed-off-by:
Jens Axboe <axboe@kernel.dk> [bwh: Despite what the "Fixes" field says, a buffer overrun was already possible if the sense data was really > 64 bytes long. Backported to 4.4: - We always need to allocate a sense buffer in order to call scsi_normalize_sense() - Remove the existing conditional heap-allocation of the sense buffer] Signed-off-by:
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Kees Cook authored
commit 7d63fb3a upstream. This removes needless use of '%p', and refactors the printk calls to use pr_*() helpers instead. Signed-off-by:
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by:
Christoph Hellwig <hch@lst.de> [bwh: Backported to 4.4: - Adjust filename - Remove "swiotlb: " prefix from an additional log message] Signed-off-by:
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Mike Kravetz authored
commit 5df63c2a upstream. This is a fix for a regression in 32 bit kernels caused by an invalid check for pgoff overflow in hugetlbfs mmap setup. The check incorrectly specified that the size of a loff_t was the same as the size of a long. The regression prevents mapping hugetlbfs files at offsets greater than 4GB on 32 bit kernels. On 32 bit kernels conversion from a page based unsigned long can not overflow a loff_t byte offset. Therefore, skip this check if sizeof(unsigned long) != sizeof(loff_t). Link: http://lkml.kernel.org/r/20180330145402.5053-1-mike.kravetz@oracle.com Fixes: 63489f8e ("hugetlbfs: check for pgoff value overflow") Reported-by:
Dan Rue <dan.rue@linaro.org> Signed-off-by:
Mike Kravetz <mike.kravetz@oracle.com> Tested-by:
Anders Roxell <anders.roxell@linaro.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Yisheng Xie <xieyisheng1@huawei.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Nic Losby <blurbdust@gmail.com> Signed-off-by:
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Mike Kravetz authored
commit 63489f8e upstream. A vma with vm_pgoff large enough to overflow a loff_t type when converted to a byte offset can be passed via the remap_file_pages system call. The hugetlbfs mmap routine uses the byte offset to calculate reservations and file size. A sequence such as: mmap(0x20a00000, 0x600000, 0, 0x66033, -1, 0); remap_file_pages(0x20a00000, 0x600000, 0, 0x20000000000000, 0); will result in the following when task exits/file closed, kernel BUG at mm/hugetlb.c:749! Call Trace: hugetlbfs_evict_inode+0x2f/0x40 evict+0xcb/0x190 __dentry_kill+0xcb/0x150 __fput+0x164/0x1e0 task_work_run+0x84/0xa0 exit_to_usermode_loop+0x7d/0x80 do_syscall_64+0x18b/0x190 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 The overflowed pgoff value causes hugetlbfs to try to set up a mapping with a negative range (end < start) that leaves invalid state which causes the BUG. The previous overflow fix to this code was incomplete and did not take the remap_file_pages system call into account. [mike.kravetz@oracle.com: v3] Link: http://lkml.kernel.org/r/20180309002726.7248-1-mike.kravetz@oracle.com [akpm@linux-foundation.org: include mmdebug.h] [akpm@linux-foundation.org: fix -ve left shift count on sh] Link: http://lkml.kernel.org/r/20180308210502.15952-1-mike.kravetz@oracle.com Fixes: 045c7a3f ("hugetlbfs: fix offset overflow in hugetlbfs mmap") Signed-off-by:
Nic Losby <blurbdust@gmail.com> Acked-by:
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Mike Kravetz authored
commit 045c7a3f upstream. If mmap() maps a file, it can be passed an offset into the file at which the mapping is to start. Offset could be a negative value when represented as a loff_t. The offset plus length will be used to update the file size (i_size) which is also a loff_t. Validate the value of offset and offset + length to make sure they do not overflow and appear as negative. Found by syzcaller with commit ff8c0c53 ("mm/hugetlb.c: don't call region_abort if region_chg fails") applied. Prior to this commit, the overflow would still occur but we would luckily return ENOMEM. To reproduce: mmap(0, 0x2000, 0, 0x40021, 0xffffffffffffffffULL, 0x8000000000000000ULL); Resulted in, kernel BUG at mm/hugetlb.c:742! Call Trace: hugetlbfs_evict_inode+0x80/0xa0 evict+0x24a/0x620 iput+0x48f/0x8c0 dentry_unlink_inode+0x31f/0x4d0 __dentry_kill+0x292/0x5e0 dput+0x730/0x830 __fput+0x438/0x720 ____fput+0x1a/0x20 task_work_run+0xfe/0x180 exit_to_usermode_loop+0x133/0x150 syscall_return_slowpath+0x184/0x1c0 entry_SYSCALL_64_fastpath+0xab/0xad Fixes: ff8c0c53 ("mm/hugetlb.c: don't call region_abort if region_chg fails") Link: http://lkml.kernel.org/r/1491951118-30678-1-git-send-email-mike.kravetz@oracle.comReported-by:
Vegard Nossum <vegard.nossum@oracle.com> Signed-off-by:
Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by:
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Mike Kravetz authored
commit ff8c0c53 upstream. Changes to hugetlbfs reservation maps is a two step process. The first step is a call to region_chg to determine what needs to be changed, and prepare that change. This should be followed by a call to call to region_add to commit the change, or region_abort to abort the change. The error path in hugetlb_reserve_pages called region_abort after a failed call to region_chg. As a result, the adds_in_progress counter in the reservation map is off by 1. This is caught by a VM_BUG_ON in resv_map_release when the reservation map is freed. syzkaller fuzzer (when using an injected kmalloc failure) found this bug, that resulted in the following: kernel BUG at mm/hugetlb.c:742! Call Trace: hugetlbfs_evict_inode+0x7b/0xa0 fs/hugetlbfs/inode.c:493 evict+0x481/0x920 fs/inode.c:553 iput_final fs/inode.c:1515 [inline] iput+0x62b/0xa20 fs/inode.c:1542 hugetlb_file_setup+0x593/0x9f0 fs/hugetlbfs/inode.c:1306 newseg+0x422/0xd30 ipc/shm.c:575 ipcget_new ipc/util.c:285 [inline] ipcget+0x21e/0x580 ipc/util.c:639 SYSC_shmget ipc/shm.c:673 [inline] SyS_shmget+0x158/0x230 ipc/shm.c:657 entry_SYSCALL_64_fastpath+0x1f/0xc2 RIP: resv_map_release+0x265/0x330 mm/hugetlb.c:742 Link: http://lkml.kernel.org/r/1490821682-23228-1-git-send-email-mike.kravetz@oracle.comSigned-off-by:
Dmitry Vyukov <dvyukov@google.com> Acked-by:
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Thomas Gleixner authored
commit 78c9c4df upstream. The posix timer overrun handling is broken because the forwarding functions can return a huge number of overruns which does not fit in an int. As a consequence timer_getoverrun(2) and siginfo::si_overrun can turn into random number generators. The k_clock::timer_forward() callbacks return a 64 bit value now. Make k_itimer::ti_overrun[_last] 64bit as well, so the kernel internal accounting is correct. 3Remove the temporary (int) casts. Add a helper function which clamps the overrun value returned to user space via timer_getoverrun(2) or siginfo::si_overrun limited to a positive value between 0 and INT_MAX. INT_MAX is an indicator for user space that the overrun value has been clamped. Reported-by:
Team OWL337 <icytxw@gmail.com> Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Acked-by:
John Stultz <john.stultz@linaro.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Link: https://lkml.kernel.org/r/20180626132705.018623573@linutronix.de [florian: Make patch apply to v4.9.135] Signed-off-by:
Florian Fainelli <f.fainelli@gmail.com> Reviewed-by:
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Lior David authored
commit b5a8ffca upstream. Add a length check in wmi_set_ie to detect unsigned integer overflow. Signed-off-by:
Lior David <qca_liord@qca.qualcomm.com> Signed-off-by:
Maya Erez <qca_merez@qca.qualcomm.com> Signed-off-by:
Kalle Valo <kvalo@qca.qualcomm.com> Signed-off-by:
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Alexei Starovoitov authored
commit af86ca4e upstream. Detect code patterns where malicious 'speculative store bypass' can be used and sanitize such patterns. 39: (bf) r3 = r10 40: (07) r3 += -216 41: (79) r8 = *(u64 *)(r7 +0) // slow read 42: (7a) *(u64 *)(r10 -72) = 0 // verifier inserts this instruction 43: (7b) *(u64 *)(r8 +0) = r3 // this store becomes slow due to r8 44: (79) r1 = *(u64 *)(r6 +0) // cpu speculatively executes this load 45: (71) r2 = *(u8 *)(r1 +0) // speculatively arbitrary 'load byte' // is now sanitized Above code after x86 JIT becomes: e5: mov %rbp,%rdx e8: add $0xffffffffffffff28,%rdx ef: mov 0x0(%r13),%r14 f3: movq $0x0,-0x48(%rbp) fb: mov %rdx,0x0(%r14) ff: mov 0x0(%rbx),%rdi 103: movzbq 0x0(%rdi),%rsi Signed-off-by:
Alexei Starovoitov <ast@kernel.org> Signed-off-by:
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Ben Hutchings authored
Extracted from commit 31fd8581 "bpf: permits narrower load from bpf program context fields". Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Alexei Starovoitov <ast@kernel.org> Signed-off-by:
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Ben Hutchings authored
Extracted from commit dc503a8a "bpf/verifier: track liveness for pruning". Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Alexei Starovoitov <ast@kernel.org> Signed-off-by:
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Alexei Starovoitov authored
commit cedaf52693f02372010548c63b2e63228b959099 upstream. The verifier supported only 4-byte metafields in struct __sk_buff and struct xdp_md. The metafields in upcoming struct bpf_perf_event are 8-byte to match register width in struct pt_regs. Teach verifier to recognize 8-byte metafield access. The patch doesn't affect safety of sockets and xdp programs. They check for 4-byte only ctx access before these conditions are hit. Signed-off-by:
Daniel Borkmann <daniel@iogearbox.net> Signed-off-by:
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Tom Lendacky authored
commit bc226f07 upstream. Expose the new virtualized architectural mechanism, VIRT_SSBD, for using speculative store bypass disable (SSBD) under SVM. This will allow guests to use SSBD on hardware that uses non-architectural mechanisms for enabling SSBD. [ tglx: Folded the migration fixup from Paolo Bonzini ] Signed-off-by:
Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by:
David Woodhouse <dwmw@amazon.co.uk> Signed-off-by:
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Borislav Petkov authored
commit e7c587da upstream. Intel and AMD have different CPUID bits hence for those use synthetic bits which get set on the respective vendor's in init_speculation_control(). So that debacles like what the commit message of c65732e4 ("x86/cpu: Restore CPUID_8000_0008_EBX reload") talks about don't happen anymore. Signed-off-by:
Borislav Petkov <bp@suse.de> Signed-off-by:
Jörg Otte <jrg.otte@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Link: https://lkml.kernel.org/r/20180504161815.GG9257@pd.tnicSigned-off-by:
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Thomas Gleixner authored
commit ccbcd267 upstream. AMD is proposing a VIRT_SPEC_CTRL MSR to handle the Speculative Store Bypass Disable via MSR_AMD64_LS_CFG so that guests do not have to care about the bit position of the SSBD bit and thus facilitate migration. Also, the sibling coordination on Family 17H CPUs can only be done on the host. Extend x86_spec_ctrl_set_guest() and x86_spec_ctrl_restore_host() with an extra argument for the VIRT_SPEC_CTRL MSR. Hand in 0 from VMX and in SVM add a new virt_spec_ctrl member to the CPU data structure which is going to be used in later patches for the actual implementation. Signed-off-by:
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Thomas Gleixner authored
commit 15e6c22f upstream. svm_vcpu_run() invokes x86_spec_ctrl_restore_host() after VMEXIT, but before the host GS is restored. x86_spec_ctrl_restore_host() uses 'current' to determine the host SSBD state of the thread. 'current' is GS based, but host GS is not yet restored and the access causes a triple fault. Move the call after the host GS restore. Fixes: 885f82bf x86/process: Allow runtime control of Speculative Store Bypass Signed-off-by:
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Konrad Rzeszutek Wilk authored
commit da39556f upstream. Expose the CPUID.7.EDX[31] bit to the guest, and also guard against various combinations of SPEC_CTRL MSR values. The handling of the MSR (to take into account the host value of SPEC_CTRL Bit(2)) is taken care of in patch: KVM/SVM/VMX/x86/spectre_v2: Support the combination of guest and host IBRS Signed-off-by:
Ingo Molnar <mingo@kernel.org> [dwmw2: Handle 4.9 guest CPUID differences, rename guest_cpu_has_ibrs() → guest_cpu_has_spec_ctrl()] Signed-off-by:
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Konrad Rzeszutek Wilk authored
commit 5cf68754 upstream. A guest may modify the SPEC_CTRL MSR from the value used by the kernel. Since the kernel doesn't use IBRS, this means a value of zero is what is needed in the host. But the 336996-Speculative-Execution-Side-Channel-Mitigations.pdf refers to the other bits as reserved so the kernel should respect the boot time SPEC_CTRL value and use that. This allows to deal with future extensions to the SPEC_CTRL interface if any at all. Note: This uses wrmsrl() instead of native_wrmsl(). I does not make any difference as paravirt will over-write the callq *0xfff.. with the wrmsrl assembler code. Signed-off-by:
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Dan Williams authored
commit 304ec1b0 upstream. Quoting Linus: I do think that it would be a good idea to very expressly document the fact that it's not that the user access itself is unsafe. I do agree that things like "get_user()" want to be protected, but not because of any direct bugs or problems with get_user() and friends, but simply because get_user() is an excellent source of a pointer that is obviously controlled from a potentially attacking user space. So it's a prime candidate for then finding _subsequent_ accesses that can then be used to perturb the cache. __uaccess_begin_nospec() covers __get_user() and copy_from_iter() where the limit check is far away from the user pointer de-reference. In those cases a barrier_nospec() prevents speculation with a potential pointer to privileged memory. uaccess_try_nospec covers get_user_try. Suggested-by:
Andi Kleen <ak@linux.intel.com> Signed-off-by:
Dan Williams <dan.j.williams@intel.com> Signed-off-by:
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Dan Williams authored
commit b5c4ae4f upstream. In preparation for converting some __uaccess_begin() instances to __uacess_begin_nospec(), make sure all 'from user' uaccess paths are using the _begin(), _end() helpers rather than open-coded stac() and clac(). No functional changes. Suggested-by:
Ingo Molnar <mingo@redhat.com> Signed-off-by:
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