Re: KASAN: use-after-free Read in perf_trace_lock_acquire

[Dmitry Vyukov]

#syz upstream

On Mon, Oct 30, 2017 at 10:53 PM, syzbot
<bot+eec541c6a1e7663177fcb48a5814c0a0776c9f68@xxxxxxxxxxxxxxxxxxxxxxxxx>
wrote:
> Hello,
>
> syzkaller hit the following crash on
> dbeb1a8ff547ffc2db69b44b4445a9eadc025abf
> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
>
>
>
>
> netlink: 5 bytes leftover after parsing attributes in process
> `syz-executor6'.
> ==================================================================
> BUG: KASAN: use-after-free in perf_trace_lock_acquire+0x8cf/0x900
> include/trace/events/lock.h:12
> Read of size 8 at addr ffff8801c7497a40 by task syz-executor4/3410
>
> CPU: 1 PID: 3410 Comm: syz-executor4 Not tainted 4.14.0-rc3+ #29
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:16 [inline]
>  dump_stack+0x194/0x257 lib/dump_stack.c:52
>  print_address_description+0x73/0x250 mm/kasan/report.c:252
>  kasan_report_error mm/kasan/report.c:351 [inline]
>  kasan_report+0x25b/0x340 mm/kasan/report.c:409
>  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
>  perf_trace_lock_acquire+0x8cf/0x900 include/trace/events/lock.h:12
>  trace_lock_acquire include/trace/events/lock.h:12 [inline]
>  lock_acquire+0x394/0x580 kernel/locking/lockdep.c:4001
>  __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
>  _raw_spin_lock_irq+0x5e/0x80 kernel/locking/spinlock.c:167
>  exit_pi_state_list+0x369/0x7a0 kernel/futex.c:914
>  mm_release+0x46d/0x590 kernel/fork.c:1144
>  exit_mm kernel/exit.c:499 [inline]
>  do_exit+0x481/0x1af0 kernel/exit.c:852
>  do_group_exit+0x149/0x400 kernel/exit.c:968
>  get_signal+0x73f/0x16d0 kernel/signal.c:2334
>  do_signal+0x94/0x1ee0 arch/x86/kernel/signal.c:808
>  exit_to_usermode_loop+0x214/0x310 arch/x86/entry/common.c:158
>  prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
>  syscall_return_slowpath arch/x86/entry/common.c:266 [inline]
>  do_syscall_32_irqs_on arch/x86/entry/common.c:335 [inline]
>  do_fast_syscall_32+0x83e/0xf05 arch/x86/entry/common.c:391
>  entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:124
> RIP: 0023:0xf7f71c79
> RSP: 002b:00000000f774c12c EFLAGS: 00000292 ORIG_RAX: 00000000000000f0
> RAX: 0000000000000000 RBX: 0000000008128088 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
>
> Allocated by task 3426:
>  save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
>  save_stack+0x43/0xd0 mm/kasan/kasan.c:447
>  set_track mm/kasan/kasan.c:459 [inline]
>  kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
>  kmem_cache_alloc_trace+0x136/0x750 mm/slab.c:3627
>  kmalloc include/linux/slab.h:493 [inline]
>  kzalloc include/linux/slab.h:666 [inline]
>  refill_pi_state_cache.part.6+0xa5/0x2f0 kernel/futex.c:790
>  refill_pi_state_cache kernel/futex.c:1810 [inline]
>  futex_requeue+0x1887/0x2370 kernel/futex.c:1877
>  do_futex+0x7f5/0x20d0 kernel/futex.c:3488
>  C_SYSC_futex kernel/futex_compat.c:200 [inline]
>  compat_SyS_futex+0x27f/0x380 kernel/futex_compat.c:174
>  do_syscall_32_irqs_on arch/x86/entry/common.c:329 [inline]
>  do_fast_syscall_32+0x3f2/0xf05 arch/x86/entry/common.c:391
>  entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:124
>
> Freed by task 3417:
>  save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
>  save_stack+0x43/0xd0 mm/kasan/kasan.c:447
>  set_track mm/kasan/kasan.c:459 [inline]
>  kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
>  __cache_free mm/slab.c:3503 [inline]
>  kfree+0xca/0x250 mm/slab.c:3820
>  put_pi_state+0x3f4/0x560 kernel/futex.c:852
>  unqueue_me_pi+0x4a/0xc0 kernel/futex.c:2266
>  futex_wait_requeue_pi.constprop.19+0xc7f/0x1300 kernel/futex.c:3185
>  do_futex+0x825/0x20d0 kernel/futex.c:3485
>  C_SYSC_futex kernel/futex_compat.c:200 [inline]
>  compat_SyS_futex+0x27f/0x380 kernel/futex_compat.c:174
>  do_syscall_32_irqs_on arch/x86/entry/common.c:329 [inline]
>  do_fast_syscall_32+0x3f2/0xf05 arch/x86/entry/common.c:391
>  entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:124
>
> The buggy address belongs to the object at ffff8801c7497a00
>  which belongs to the cache kmalloc-256 of size 256
> The buggy address is located 64 bytes inside of
>  256-byte region [ffff8801c7497a00, ffff8801c7497b00)
> The buggy address belongs to the page:
> page:ffffea00071d25c0 count:1 mapcount:0 mapping:ffff8801c7497000 index:0x0
> flags: 0x200000000000100(slab)
> raw: 0200000000000100 ffff8801c7497000 0000000000000000 000000010000000c
> raw: ffffea00071ebf60 ffffea00071d6920 ffff8801dac007c0 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
>  ffff8801c7497900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff8801c7497980: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>>
>> ffff8801c7497a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>
>                                            ^
>  ffff8801c7497a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff8801c7497b00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
> ==================================================================
>
>
> ---
> This bug is generated by a dumb bot. It may contain errors.
> See https://goo.gl/tpsmEJ for details.
> Direct all questions to syzkaller@xxxxxxxxxxxxxxxxx
>
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