KASAN: use-after-free Read in __lock_acquire

[syzbot]

Hello,

syzkaller hit the following crash on
887c8ba753fbe809ba93fa3cfd0cc46db18d37d4
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.

syzkaller reproducer is attached. See https://goo.gl/kgGztJ
for information about syzkaller reproducers
CC: [dvh...@infradead.org linux-...@vger.kernel.org mi...@redhat.com
pet...@infradead.org tg...@linutronix.de]

BUG: KASAN: use-after-free in __lock_acquire+0x407b/0x4620
kernel/locking/lockdep.c:3376
Read of size 8 at addr ffff8801ce6080a8 by task syz-executor6/3264

CPU: 1 PID: 3264 Comm: syz-executor6 Not tainted 4.14.0-rc3+ #23
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
__lock_acquire+0x407b/0x4620 kernel/locking/lockdep.c:3376
lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4002
__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:1126
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: 0023:0xf7fcac79
RSP: 002b:00000000f7fc612c EFLAGS: 00000292 ORIG_RAX: 00000000000000f0
RAX: fffffffffffffe00 RBX: 0000000008128018 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 3288:
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 3276:
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 ffff8801ce608080
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 40 bytes inside of
256-byte region [ffff8801ce608080, ffff8801ce608180)
The buggy address belongs to the page:
page:ffffea0007398200 count:1 mapcount:0 mapping:ffff8801ce608080 index:0x0
flags: 0x200000000000100(slab)
raw: 0200000000000100 ffff8801ce608080 0000000000000000 000000010000000c
raw: ffffea00073929a0 ffffea000739d8e0 ffff8801dac007c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8801ce607f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8801ce608000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffff8801ce608080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8801ce608100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801ce608180: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
==================================================================


---
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[Dmitry Vyukov]

#syz fix: futex: Fix more put_pi_state() vs. exit_pi_state_list() races


On Wed, Nov 1, 2017 at 9:04 PM, syzbot
<bot+db13ba129047352527...@syzkaller.appspotmail.com>
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