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  1. 05 Apr, 2021 1 commit
  3. 04 Apr, 2021 2 commits
    • Linus Torvalds's avatar
      Linux 5.12-rc6 · e49d033b
      Linus Torvalds authored
      e49d033b
    • Zheyu Ma's avatar
      firewire: nosy: Fix a use-after-free bug in nosy_ioctl() · 829933ef
      Zheyu Ma authored 
      For each device, the nosy driver allocates a pcilynx structure.
A use-after-free might happen in the following scenario:

 1. Open nosy device for the first time and call ioctl with command
    NOSY_IOC_START, then a new client A will be malloced and added to
    doubly linked list.
 2. Open nosy device for the second time and call ioctl with command
    NOSY_IOC_START, then a new client B will be malloced and added to
    doubly linked list.
 3. Call ioctl with command NOSY_IOC_START for client A, then client A
    will be readded to the doubly linked list. Now the doubly linked
    list is messed up.
 4. Close the first nosy device and nosy_release will be called. In
    nosy_release, client A will be unlinked and freed.
 5. Close the second nosy device, and client A will be referenced,
    resulting in UAF.

The root cause of this bug is that the element in the doubly linked list
is reentered into the list.

Fix this bug by adding a check before inserting a client.  If a client
is already in the linked list, don't insert it.

The following KASAN report reveals it:

   BUG: KASAN: use-after-free in nosy_release+0x1ea/0x210
   Write of size 8 at addr ffff888102ad7360 by task poc
   CPU: 3 PID: 337 Comm: poc Not tainted 5.12.0-rc5+ #6
   Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
   Call Trace:
     nosy_release+0x1ea/0x210
     __fput+0x1e2/0x840
     task_work_run+0xe8/0x180
     exit_to_user_mode_prepare+0x114/0x120
     syscall_exit_to_user_mode+0x1d/0x40
     entry_SYSCALL_64_after_hwframe+0x44/0xae

   Allocated by task 337:
     nosy_open+0x154/0x4d0
     misc_open+0x2ec/0x410
     chrdev_open+0x20d/0x5a0
     do_dentry_open+0x40f/0xe80
     path_openat+0x1cf9/0x37b0
     do_filp_open+0x16d/0x390
     do_sys_openat2+0x11d/0x360
     __x64_sys_open+0xfd/0x1a0
     do_syscall_64+0x33/0x40
     entry_SYSCALL_64_after_hwframe+0x44/0xae

   Freed by task 337:
     kfree+0x8f/0x210
     nosy_release+0x158/0x210
     __fput+0x1e2/0x840
     task_work_run+0xe8/0x180
     exit_to_user_mode_prepare+0x114/0x120
     syscall_exit_to_user_mode+0x1d/0x40
     entry_SYSCALL_64_after_hwframe+0x44/0xae

   The buggy address belongs to the object at ffff888102ad7300 which belongs to the cache kmalloc-128 of size 128
   The buggy address is located 96 bytes inside of 128-byte region [ffff888102ad7300, ffff888102ad7380)

[ Modified to use 'list_empty()' inside proper lock  - Linus ]

Link: https://lore.kernel.org/lkml/1617433116-5930-1-git-send-email-zheyuma97@gmail.com/Reported-and-tested-by: default avatar马哲宇 (Zheyu Ma) <zheyuma97@gmail.com>
Signed-off-by: default avatarZheyu Ma <zheyuma97@gmail.com>
Cc: Greg Kroah-Hartman <greg@kroah.com>
Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      829933ef
  5. 03 Apr, 2021 14 commits
  7. 02 Apr, 2021 17 commits
    • Linus Torvalds's avatar
      Merge tag 'block-5.12-2021-04-02' of git://git.kernel.dk/linux-block · d93a0d43
      Linus Torvalds authored 
      Pull block fixes from Jens Axboe:

 - Remove comment that never came to fruition in 22 years of development
   (Christoph)

 - Remove unused request flag (Christoph)

 - Fix for null_blk fake timeout handling (Damien)

 - Fix for IOCB_NOWAIT being ignored for O_DIRECT on raw bdevs (Pavel)

 - Error propagation fix for multiple split bios (Yufen)

* tag 'block-5.12-2021-04-02' of git://git.kernel.dk/linux-block:
  block: remove the unused RQF_ALLOCED flag
  block: update a few comments in uapi/linux/blkpg.h
  block: don't ignore REQ_NOWAIT for direct IO
  null_blk: fix command timeout completion handling
  block: only update parent bi_status when bio fail
      d93a0d43
    • Linus Torvalds's avatar
      Merge tag 'io_uring-5.12-2021-04-02' of git://git.kernel.dk/linux-block · 1faccb63
      Linus Torvalds authored 
      Pull io_uring fixes from Jens Axboe:
 "Nothing really major in here, and finally nothing really related to
  signals. A few minor fixups related to the threading changes, and some
  general fixes, that's it.

  There's the pending gdb-get-confused-about-arch, but that's more of a
  cosmetic issue, nothing that hinder use of it. And given that other
  archs will likely be affected by that oddity too, better to postpone
  any changes there until 5.13 imho"

* tag 'io_uring-5.12-2021-04-02' of git://git.kernel.dk/linux-block:
  io_uring: move reissue into regular IO path
  io_uring: fix EIOCBQUEUED iter revert
  io_uring/io-wq: protect against sprintf overflow
  io_uring: don't mark S_ISBLK async work as unbounded
  io_uring: drop sqd lock before handling signals for SQPOLL
  io_uring: handle setup-failed ctx in kill_timeouts
  io_uring: always go for cancellation spin on exec
      1faccb63
    • Linus Torvalds's avatar
      Merge tag 'acpi-5.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm · 0a84c2e4
      Linus Torvalds authored 
      Pull ACPI fixes from Rafael Wysocki:
 "These fix an ACPI tables management issue, an issue related to the
  ACPI enumeration of devices and CPU wakeup in the ACPI processor
  driver.

  Specifics:

   - Ensure that the memory occupied by ACPI tables on x86 will always
     be reserved to prevent it from being allocated for other purposes
     which was possible in some cases (Rafael Wysocki).

   - Fix the ACPI device enumeration code to prevent it from attempting
     to evaluate the _STA control method for devices with unmet
     dependencies which is likely to fail (Hans de Goede).

   - Fix the handling of CPU0 wakeup in the ACPI processor driver to
     prevent CPU0 online failures from occurring (Vitaly Kuznetsov)"

* tag 'acpi-5.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI: processor: Fix CPU0 wakeup in acpi_idle_play_dead()
  ACPI: scan: Fix _STA getting called on devices with unmet dependencies
  ACPI: tables: x86: Reserve memory occupied by ACPI tables
      0a84c2e4
    • Linus Torvalds's avatar
      Merge tag 'pm-5.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm · 9314a0e9
      Linus Torvalds authored 
      Pull power management fixes from Rafael Wysocki:
 "These fix a race condition and an ordering issue related to using
  device links in the runtime PM framework and two kerneldoc comments in
  cpufreq.

  Specifics:

   - Fix race condition related to the handling of supplier devices
     during consumer device probe and fix the order of decrementation of
     two related reference counters in the runtime PM core code handling
     supplier devices (Adrian Hunter).

   - Fix kerneldoc comments in cpufreq that have not been updated along
     with the functions documented by them (Geert Uytterhoeven)"

* tag 'pm-5.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  PM: runtime: Fix race getting/putting suppliers at probe
  PM: runtime: Fix ordering in pm_runtime_get_suppliers()
  cpufreq: Fix scaling_{available,boost}_frequencies_show() comments
      9314a0e9
    • Christoph Hellwig's avatar
      block: remove the unused RQF_ALLOCED flag · f06c6096
      Christoph Hellwig authored 
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      f06c6096
    • Christoph Hellwig's avatar
      block: update a few comments in uapi/linux/blkpg.h · b9c6cdc3
      Christoph Hellwig authored 
      The big top of the file comment talk about grand plans that never
happened, so remove them to not confuse the readers.  Also mark the
devname and volname fields as ignored as they were never used by the
kernel.
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      b9c6cdc3
    • Linus Torvalds's avatar
      Merge tag 'trace-v5.12-rc5-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace · 05de4538
      Linus Torvalds authored 
      Pull tracing fix from Steven Rostedt:
 "Fix stack trace entry size to stop showing garbage

  The macro that creates both the structure and the format displayed to
  user space for the stack trace event was changed a while ago to fix
  the parsing by user space tooling. But this change also modified the
  structure used to store the stack trace event. It changed the caller
  array field from [0] to [8].

  Even though the size in the ring buffer is dynamic and can be
  something other than 8 (user space knows how to handle this), the 8
  extra words was not accounted for when reserving the event on the ring
  buffer, and added 8 more entries, due to the calculation of
  "sizeof(*entry) + nr_entries * sizeof(long)", as the sizeof(*entry)
  now contains 8 entries.

  The size of the caller field needs to be subtracted from the size of
  the entry to create the correct allocation size"

* tag 'trace-v5.12-rc5-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Fix stack trace event size
      05de4538
    • Jens Axboe's avatar
      io_uring: move reissue into regular IO path · 230d50d4
      Jens Axboe authored 
      It's non-obvious how retry is done for block backed files, when it happens
off the kiocb done path. It also makes it tricky to deal with the iov_iter
handling.

Just mark the req as needing a reissue, and handling it from the
submission path instead. This makes it directly obvious that we're not
re-importing the iovec from userspace past the submit point, and it means
that we can just reuse our usual -EAGAIN retry path from the read/write
handling.

At some point in the future, we'll gain the ability to always reliably
return -EAGAIN through the stack. A previous attempt on the block side
didn't pan out and got reverted, hence the need to check for this
information out-of-band right now.
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      230d50d4
    • Rafael J. Wysocki's avatar
      Merge branches 'acpi-tables' and 'acpi-scan' · 91463ebf
      Rafael J. Wysocki authored 
      * acpi-tables:
  ACPI: tables: x86: Reserve memory occupied by ACPI tables

* acpi-scan:
  ACPI: scan: Fix _STA getting called on devices with unmet dependencies
      91463ebf
    • Rafael J. Wysocki's avatar
      Merge branch 'pm-cpufreq' · ac1790ad
      Rafael J. Wysocki authored 
      * pm-cpufreq:
  cpufreq: Fix scaling_{available,boost}_frequencies_show() comments
      ac1790ad
    • Pavel Begunkov's avatar
      block: don't ignore REQ_NOWAIT for direct IO · f8b78caf
      Pavel Begunkov authored 
      If IOCB_NOWAIT is set on submission, then that needs to get propagated to
REQ_NOWAIT on the block side. Otherwise we completely lose this
information, and any issuer of IOCB_NOWAIT IO will potentially end up
blocking on eg request allocation on the storage side.
Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      f8b78caf
    • Kefeng Wang's avatar
      riscv: Make NUMA depend on MMU · 1adbc294
      Kefeng Wang authored 
      NUMA is useless when NOMMU, and it leads some build error,
make it depend on MMU.
Reported-by: default avatarkernel test robot <lkp@intel.com>
Signed-off-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
      1adbc294
    • Yang Li's avatar
      riscv: remove unneeded semicolon · 9d8c7d92
      Yang Li authored 
      Eliminate the following coccicheck warning:
./arch/riscv/mm/kasan_init.c:219:2-3: Unneeded semicolon
Reported-by: default avatarAbaci Robot <abaci@linux.alibaba.com>
Signed-off-by: default avatarYang Li <yang.lee@linux.alibaba.com>
Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
      9d8c7d92
    • Zihao Yu's avatar
      riscv,entry: fix misaligned base for excp_vect_table · ac8d0b90
      Zihao Yu authored 
      In RV64, the size of each entry in excp_vect_table is 8 bytes. If the
base of the table is not 8-byte aligned, loading an entry in the table
will raise a misaligned exception. Although such exception will be
handled by opensbi/bbl, this still causes performance degradation.
Signed-off-by: default avatarZihao Yu <yuzihao@ict.ac.cn>
Reviewed-by: default avatarAnup Patel <anup@brainfault.org>
Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
      ac8d0b90
    • Ben Dooks's avatar
      riscv: evaluate put_user() arg before enabling user access · 285a76bb
      Ben Dooks authored 
      The <asm/uaccess.h> header has a problem with put_user(a, ptr) if
the 'a' is not a simple variable, such as a function. This can lead
to the compiler producing code as so:

1:	enable_user_access()
2:	evaluate 'a' into register 'r'
3:	put 'r' to 'ptr'
4:	disable_user_acess()

The issue is that 'a' is now being evaluated with the user memory
protections disabled. So we try and force the evaulation by assigning
'x' to __val at the start, and hoping the compiler barriers in
 enable_user_access() do the job of ordering step 2 before step 1.

This has shown up in a bug where 'a' sleeps and thus schedules out
and loses the SR_SUM flag. This isn't sufficient to fully fix, but
should reduce the window of opportunity. The first instance of this
we found is in scheudle_tail() where the code does:

$ less -N kernel/sched/core.c

4263  if (current->set_child_tid)
4264         put_user(task_pid_vnr(current), current->set_child_tid);

Here, the task_pid_vnr(current) is called within the block that has
enabled the user memory access. This can be made worse with KASAN
which makes task_pid_vnr() a rather large call with plenty of
opportunity to sleep.
Signed-off-by: default avatarBen Dooks <ben.dooks@codethink.co.uk>
Reported-by: syzbot+e74b94fe601ab9552d69@syzkaller.appspotmail.com
Suggested-by: default avatarArnd Bergman <arnd@arndb.de>

--
Changes since v1:
- fixed formatting and updated the patch description with more info

Changes since v2:
- fixed commenting on __put_user() (schwab@linux-m68k.org)

Change since v3:
- fixed RFC in patch title. Should be ready to merge.
Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
      285a76bb
    • Kefeng Wang's avatar
      riscv: Drop const annotation for sp · 23c1075a
      Kefeng Wang authored 
      The const annotation should not be used for 'sp', or it will
become read only and lead to bad stack output.

Fixes: dec82277 ("riscv: stacktrace: Move register keyword to beginning of declaration")
Signed-off-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
      23c1075a
    • Linus Torvalds's avatar
      Merge tag 'lto-v5.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux · 1678e493
      Linus Torvalds authored 
      Pull LTO fix from Kees Cook:
 "It seems that there is a bug in ld.bfd when doing module section
  merging.

  As explicit merging is only needed for LTO, the work-around is to only
  do it under LTO, leaving the original section layout choices alone
  under normal builds:

   - Only perform explicit module section merges under LTO (Sean
     Christopherson)"

* tag 'lto-v5.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  kbuild: lto: Merge module sections if and only if CONFIG_LTO_CLANG is enabled
      1678e493
  9. 01 Apr, 2021 6 commits
    • Sean Christopherson's avatar
      kbuild: lto: Merge module sections if and only if CONFIG_LTO_CLANG is enabled · 6a3193cd
      Sean Christopherson authored 
      Merge module sections only when using Clang LTO. With ld.bfd, merging
sections does not appear to update the symbol tables for the module,
e.g. 'readelf -s' shows the value that a symbol would have had, if
sections were not merged. ld.lld does not show this problem.

The stale symbol table breaks gdb's function disassembler, and presumably
other things, e.g.

  gdb -batch -ex "file arch/x86/kvm/kvm.ko" -ex "disassemble kvm_init"

reads the wrong bytes and dumps garbage.

Fixes: dd277622 ("kbuild: lto: merge module sections")
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Reviewed-by: default avatarSami Tolvanen <samitolvanen@google.com>
Tested-by: default avatarSami Tolvanen <samitolvanen@google.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210322234438.502582-1-seanjc@google.com
      6a3193cd
    • Linus Torvalds's avatar
      Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm · 6905b1dc
      Linus Torvalds authored 
      Pull kvm fixes from Paolo Bonzini:
 "It's a bit larger than I (and probably you) would like by the time we
  get to -rc6, but perhaps not entirely unexpected since the changes in
  the last merge window were larger than usual.

  x86:
   - Fixes for missing TLB flushes with TDP MMU

   - Fixes for race conditions in nested SVM

   - Fixes for lockdep splat with Xen emulation

   - Fix for kvmclock underflow

   - Fix srcdir != builddir builds

   - Other small cleanups

  ARM:
   - Fix GICv3 MMIO compatibility probing

   - Prevent guests from using the ARMv8.4 self-hosted tracing
     extension"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  selftests: kvm: Check that TSC page value is small after KVM_SET_CLOCK(0)
  KVM: x86: Prevent 'hv_clock->system_time' from going negative in kvm_guest_time_update()
  KVM: x86: disable interrupts while pvclock_gtod_sync_lock is taken
  KVM: x86: reduce pvclock_gtod_sync_lock critical sections
  KVM: SVM: ensure that EFER.SVME is set when running nested guest or on nested vmexit
  KVM: SVM: load control fields from VMCB12 before checking them
  KVM: x86/mmu: Don't allow TDP MMU to yield when recovering NX pages
  KVM: x86/mmu: Ensure TLBs are flushed for TDP MMU during NX zapping
  KVM: x86/mmu: Ensure TLBs are flushed when yielding during GFN range zap
  KVM: make: Fix out-of-source module builds
  selftests: kvm: make hardware_disable_test less verbose
  KVM: x86/vPMU: Forbid writing to MSR_F15H_PERF MSRs when guest doesn't have X86_FEATURE_PERFCTR_CORE
  KVM: x86: remove unused declaration of kvm_write_tsc()
  KVM: clean up the unused argument
  tools/kvm_stat: Add restart delay
  KVM: arm64: Fix CPU interface MMIO compatibility detection
  KVM: arm64: Disable guest access to trace filter controls
  KVM: arm64: Hide system instruction access to Trace registers
      6905b1dc
    • Linus Torvalds's avatar
      Merge tag 'drm-fixes-2021-04-02' of git://anongit.freedesktop.org/drm/drm · a80314c3
      Linus Torvalds authored 
      Pull drm fixes from Dave Airlie:
 "Things have settled down in time for Easter, a random smattering of
  small fixes across a few drivers.

  I'm guessing though there might be some i915 and misc fixes out there
  I haven't gotten yet, but since today is a public holiday here, I'm
  sending this early so I can have the day off, I'll see if more
  requests come in and decide what to do with them later.

  amdgpu:
   - Polaris idle power fix
   - VM fix
   - Vangogh S3 fix
   - Fixes for non-4K page sizes

  amdkfd:
   - dqm fence memory corruption fix

  tegra:
   - lockdep warning fix
   - runtine PM reference fix
   - display controller fix
   - PLL Fix

  imx:
   - memory leak in error path fix
   - LDB driver channel registration fix
   - oob array warning in LDB driver

  exynos
   - unused header file removal"

* tag 'drm-fixes-2021-04-02' of git://anongit.freedesktop.org/drm/drm:
  drm/amdgpu: check alignment on CPU page for bo map
  drm/amdgpu: Set a suitable dev_info.gart_page_size
  drm/amdgpu/vangogh: don't check for dpm in is_dpm_running when in suspend
  drm/amdkfd: dqm fence memory corruption
  drm/tegra: sor: Grab runtime PM reference across reset
  drm/tegra: dc: Restore coupling of display controllers
  gpu: host1x: Use different lock classes for each client
  drm/tegra: dc: Don't set PLL clock to 0Hz
  drm/amdgpu: fix offset calculation in amdgpu_vm_bo_clear_mappings()
  drm/amd/pm: no need to force MCLK to highest when no display connected
  drm/exynos/decon5433: Remove the unused include statements
  drm/imx: imx-ldb: fix out of bounds array access warning
  drm/imx: imx-ldb: Register LDB channel1 when it is the only channel to be used
  drm/imx: fix memory leak when fails to init
      a80314c3
    • Dave Airlie's avatar
      Merge tag 'imx-drm-fixes-2021-04-01' of git://git.pengutronix.de/git/pza/linux into drm-fixes · 6fdb8e5a
      Dave Airlie authored 
      drm/imx: imx-drm-core and imx-ldb fixes

Fix a memory leak in an error path during DRM device initialization,
fix the LDB driver to register channel 1 even if channel 0 is unused,
and fix an out of bounds array access warning in the LDB driver.
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>

From: Philipp Zabel <p.zabel@pengutronix.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20210401092235.GA13586@pengutronix.de
      6fdb8e5a
    • Dave Airlie's avatar
      Merge tag 'drm/tegra/for-5.12-rc6' of ssh://git.freedesktop.org/git/tegra/linux into drm-fixes · a0497251
      Dave Airlie authored 
      drm/tegra: Fixes for v5.12-rc6

This contains a couple of fixes for various issues such as lockdep
warnings, runtime PM references, coupled display controllers and
misconfigured PLLs.
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>

From: Thierry Reding <thierry.reding@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210401163352.3348296-1-thierry.reding@gmail.com
      a0497251
    • Steven Rostedt (VMware)'s avatar
      tracing: Fix stack trace event size · 9deb193a
      Steven Rostedt (VMware) authored 
      Commit cbc3b92c fixed an issue to modify the macros of the stack trace
event so that user space could parse it properly. Originally the stack
trace format to user space showed that the called stack was a dynamic
array. But it is not actually a dynamic array, in the way that other
dynamic event arrays worked, and this broke user space parsing for it. The
update was to make the array look to have 8 entries in it. Helper
functions were added to make it parse it correctly, as the stack was
dynamic, but was determined by the size of the event stored.

Although this fixed user space on how it read the event, it changed the
internal structure used for the stack trace event. It changed the array
size from [0] to [8] (added 8 entries). This increased the size of the
stack trace event by 8 words. The size reserved on the ring buffer was the
size of the stack trace event plus the number of stack entries found in
the stack trace. That commit caused the amount to be 8 more than what was
needed because it did not expect the caller field to have any size. This
produced 8 entries of garbage (and reading random data) from the stack
trace event:

          <idle>-0       [002] d... 1976396.837549: <stack trace>
 => trace_event_raw_event_sched_switch
 => __traceiter_sched_switch
 => __schedule
 => schedule_idle
 => do_idle
 => cpu_startup_entry
 => secondary_startup_64_no_verify
 => 0xc8c5e150ffff93de
 => 0xffff93de
 => 0
 => 0
 => 0xc8c5e17800000000
 => 0x1f30affff93de
 => 0x00000004
 => 0x200000000

Instead, subtract the size of the caller field from the size of the event
to make sure that only the amount needed to store the stack trace is
reserved.

Link: https://lore.kernel.org/lkml/your-ad-here.call-01617191565-ext-9692@work.hours/

Cc: stable@vger.kernel.org
Fixes: cbc3b92c ("tracing: Set kernel_stack's caller size properly")
Reported-by: default avatarVasily Gorbik <gor@linux.ibm.com>
Tested-by: default avatarVasily Gorbik <gor@linux.ibm.com>
Acked-by: default avatarVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
      9deb193a
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