Date:   Sat, 16 Feb 2019 18:43:39 +0800
From:   Xie XiuQi <xiexiuqi@...wei.com>
To:     Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        syzbot <syzbot+a24c397a29ad22d86c98@...kaller.appspotmail.com>,
        <acme@...nel.org>, <jolsa@...hat.com>,
        <linux-kernel@...r.kernel.org>, <mingo@...hat.com>,
        <namhyung@...nel.org>, <peterz@...radead.org>,
        <syzkaller-bugs@...glegroups.com>
CC:     Cheng Jian <cj.chengjian@...wei.com>,
        Li Bin <huawei.libin@...wei.com>,
        wangxuefeng <wxf.wang@...ilicon.com>,
        Xie XiuQi <xiexiuqi@...wei.com>
Subject: Re: KASAN: use-after-free Write in _free_event

Hi everyone,

I meet this bug two times, does anyone has idea to fix this issue ? (See attachments)

==================================================================
BUG: KASAN: use-after-free in atomic_dec_and_test include/asm-generic/atomic-instrumented.h:259 [inline]
BUG: KASAN: use-after-free in put_task_struct include/linux/sched/task.h:95 [inline]
BUG: KASAN: use-after-free in _free_event+0x2c4/0xfe0 kernel/events/core.c:4452
Write of size 4 at addr ffff8883780cd0a0 by task syz-executor0/9553

CPU: 3 PID: 9553 Comm: syz-executor0 Not tainted 4.19.18-514.55.6.9.x86_64+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xca/0x13e lib/dump_stack.c:113
 print_address_description+0x79/0x330 mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report+0x18a/0x2e0 mm/kasan/report.c:412
 atomic_dec_and_test include/asm-generic/atomic-instrumented.h:259 [inline]
 put_task_struct include/linux/sched/task.h:95 [inline]
 _free_event+0x2c4/0xfe0 kernel/events/core.c:4452
 free_event+0x41/0xa0 kernel/events/core.c:4473
 perf_event_release_kernel+0x43b/0xc70 kernel/events/core.c:4634
 perf_release+0x33/0x40 kernel/events/core.c:4648
 __fput+0x27f/0x7f0 fs/file_table.c:278
 task_work_run+0x136/0x1b0 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x850/0x2b90 kernel/exit.c:867
 do_group_exit+0x106/0x2f0 kernel/exit.c:970
 get_signal+0x62b/0x1740 kernel/signal.c:2513
 do_signal+0x94/0x16a0 arch/x86/kernel/signal.c:816
 exit_to_usermode_loop+0x108/0x1d0 arch/x86/entry/common.c:162
 prepare_exit_to_usermode+0x27b/0x2f0 arch/x86/entry/common.c:197
 retint_user+0x8/0x18
RIP: 0033:0x4021b7
Code: Bad RIP value.
RSP: 002b:00007fa7cb40cb30 EFLAGS: 00010202
RAX: 0000000000000000 RBX: 000000000000000b RCX: 0000000000462589
RDX: 00007fa7cb40cb40 RSI: ffffffffffffffb8 RDI: 000000000000000b
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00000000004bc4cd R14: 00000000006f4c70 R15: 00000000ffffffff

Allocated by task 9552:
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xa0/0xd0 mm/kasan/kasan.c:553
 slab_post_alloc_hook mm/slab.h:444 [inline]
 slab_alloc_node mm/slub.c:2706 [inline]
 kmem_cache_alloc_node+0xe3/0x2e0 mm/slub.c:2742
 alloc_task_struct_node kernel/fork.c:157 [inline]
 dup_task_struct kernel/fork.c:802 [inline]
 copy_process.part.26+0x1a98/0x6c70 kernel/fork.c:1707
 copy_process kernel/fork.c:1664 [inline]
 _do_fork+0x1c6/0xe60 kernel/fork.c:2175
 do_syscall_64+0xc8/0x580 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9552:
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x12e/0x180 mm/kasan/kasan.c:521
 slab_free_hook mm/slub.c:1371 [inline]
 slab_free_freelist_hook mm/slub.c:1398 [inline]
 slab_free mm/slub.c:2953 [inline]
 kmem_cache_free+0xbd/0x320 mm/slub.c:2969
 copy_process.part.26+0x18d9/0x6c70 kernel/fork.c:2107
 copy_process kernel/fork.c:1664 [inline]
 _do_fork+0x1c6/0xe60 kernel/fork.c:2175
 do_syscall_64+0xc8/0x580 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8883780cd080
 which belongs to the cache task_struct of size 9992
The buggy address is located 32 bytes inside of
 9992-byte region [ffff8883780cd080, ffff8883780cf788)
The buggy address belongs to the page:
page:ffffea000de03200 count:1 mapcount:0 mapping:ffff888107d07a00 index:0x0 compound_mapcount: 0
flags: 0x2fffff80008100(slab|head)
raw: 002fffff80008100 dead000000000100 dead000000000200 ffff888107d07a00
raw: 0000000000000000 0000000080030003 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8883780ccf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8883780cd000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8883780cd080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff8883780cd100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8883780cd180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


On 2018/7/9 18:11, Alexander Shishkin wrote:
> syzbot <syzbot+a24c397a29ad22d86c98@...kaller.appspotmail.com> writes:
> 
>> Hello,
>>
>> syzbot found the following crash on:
>>
>> HEAD commit:    b2d44d145d2a Merge tag '4.18-rc3-smb3fixes' of git://git.s..
>> git tree:       upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=178cf50c400000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=2ca6c7a31d407f86
>> dashboard link: https://syzkaller.appspot.com/bug?extid=a24c397a29ad22d86c98
>> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
>>
>> Unfortunately, I don't have any reproducer for this crash yet.
> 
> Is there a chance of getting a reproducer for this one?
> 
> Thanks,
> --
> Alex
> 
> .
> 

-- 
Thanks,
Xie XiuQi

View attachment "errorlog-1.txt" of type "text/plain" (4468 bytes)

View attachment "errorlog-2.txt" of type "text/plain" (4299 bytes)

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