Date:   Tue, 31 Oct 2017 14:49:02 +0300
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     syzbot 
        <bot+eec541c6a1e7663177fcb48a5814c0a0776c9f68@...kaller.appspotmail.com>
Cc:     dvhart@...radead.org, LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        syzkaller-bugs@...glegroups.com,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: KASAN: use-after-free Read in perf_trace_lock_acquire

Peter, is this dup of "WARNING in get_pi_state"?
https://groups.google.com/d/msg/syzkaller-bugs/jpui-7LJvUw/b77s8UZiAgAJ

On Tue, Oct 31, 2017 at 2:43 PM, syzbot
<bot+eec541c6a1e7663177fcb48a5814c0a0776c9f68@...kaller.appspotmail.com>
wrote:
>> #syz upstream
>
>
> Can't upstream, this is final destination.
>
>
>
>> On Mon, Oct 30, 2017 at 10:53 PM, syzbot
>> <bot+eec541c6a1e7663177fcb48a5814c0a0776c9f68@...kaller.appspotmail.com>
>> 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@...glegroups.com.
>
>
>>> syzbot will keep track of this bug report.
>>> Once a fix for this bug is committed, please reply to this email with:
>>> #syz fix: exact-commit-title
>>> To mark this as a duplicate of another syzbot report, please reply with:
>>> #syz dup: exact-subject-of-another-report
>>> If it's a one-off invalid bug report, please reply with:
>>> #syz invalid
>>> Note: if the crash happens again, it will cause creation of a new bug
>>> report.
>
>
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