[syzbot] [fs?] KCSAN: data-race in __ep_remove / __fput (4)
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syzbot
Jul 4, 2024, 10:38:22 AM (3 days ago) Jul 4
to bra...@kernel.org, ja...@suse.cz, linux-...@vger.kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com, vi...@zeniv.linux.org.uk
Hello,
syzbot found the following issue on:
HEAD commit: 22a40d14b572 Linux 6.10-rc6
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10f94dae980000
kernel config: https://syzkaller.appspot.com/x/.config?x=5b9537cd00be479e
dashboard link: https://syzkaller.appspot.com/bug?extid=3195ed1f3a2ab8bea49a
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ebe2f3933faf/disk-22a40d14.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7227032da0fe/vmlinux-22a40d14.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a330dc1e107b/bzImage-22a40d14.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3195ed...@syzkaller.appspotmail.com
==================================================================
BUG: KCSAN: data-race in __ep_remove / __fput
write to 0xffff88810f2358d0 of 8 bytes by task 6036 on cpu 1:
__ep_remove+0x3c9/0x450 fs/eventpoll.c:826
ep_remove_safe fs/eventpoll.c:864 [inline]
ep_clear_and_put+0x158/0x260 fs/eventpoll.c:900
ep_eventpoll_release+0x32/0x50 fs/eventpoll.c:937
__fput+0x2c2/0x660 fs/file_table.c:422
____fput+0x15/0x20 fs/file_table.c:450
task_work_run+0x13a/0x1a0 kernel/task_work.c:180
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0xbe/0x130 kernel/entry/common.c:218
do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
read to 0xffff88810f2358d0 of 8 bytes by task 6037 on cpu 0:
eventpoll_release include/linux/eventpoll.h:45 [inline]
__fput+0x234/0x660 fs/file_table.c:413
____fput+0x15/0x20 fs/file_table.c:450
task_work_run+0x13a/0x1a0 kernel/task_work.c:180
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0xbe/0x130 kernel/entry/common.c:218
do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
value changed: 0xffff888102f1e010 -> 0x0000000000000000
Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 6037 Comm: syz.0.1032 Not tainted 6.10.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
==================================================================
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
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If the report is already addressed, let syzbot know by replying with:
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If the report is a duplicate of another one, reply with:
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If you want to undo deduplication, reply with:
#syz undup
syzbot found the following issue on:
HEAD commit: 22a40d14b572 Linux 6.10-rc6
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10f94dae980000
kernel config: https://syzkaller.appspot.com/x/.config?x=5b9537cd00be479e
dashboard link: https://syzkaller.appspot.com/bug?extid=3195ed1f3a2ab8bea49a
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ebe2f3933faf/disk-22a40d14.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7227032da0fe/vmlinux-22a40d14.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a330dc1e107b/bzImage-22a40d14.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3195ed...@syzkaller.appspotmail.com
==================================================================
BUG: KCSAN: data-race in __ep_remove / __fput
write to 0xffff88810f2358d0 of 8 bytes by task 6036 on cpu 1:
__ep_remove+0x3c9/0x450 fs/eventpoll.c:826
ep_remove_safe fs/eventpoll.c:864 [inline]
ep_clear_and_put+0x158/0x260 fs/eventpoll.c:900
ep_eventpoll_release+0x32/0x50 fs/eventpoll.c:937
__fput+0x2c2/0x660 fs/file_table.c:422
____fput+0x15/0x20 fs/file_table.c:450
task_work_run+0x13a/0x1a0 kernel/task_work.c:180
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0xbe/0x130 kernel/entry/common.c:218
do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
read to 0xffff88810f2358d0 of 8 bytes by task 6037 on cpu 0:
eventpoll_release include/linux/eventpoll.h:45 [inline]
__fput+0x234/0x660 fs/file_table.c:413
____fput+0x15/0x20 fs/file_table.c:450
task_work_run+0x13a/0x1a0 kernel/task_work.c:180
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0xbe/0x130 kernel/entry/common.c:218
do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
value changed: 0xffff888102f1e010 -> 0x0000000000000000
Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 6037 Comm: syz.0.1032 Not tainted 6.10.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
==================================================================
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
Dmitry Vyukov
Jul 4, 2024, 10:40:55 AM (3 days ago) Jul 4
to syzbot, bra...@kernel.org, ja...@suse.cz, linux-...@vger.kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com, vi...@zeniv.linux.org.uk
On Thu, 4 Jul 2024 at 16:38, syzbot
<syzbot+3195ed...@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 22a40d14b572 Linux 6.10-rc6
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=10f94dae980000
> kernel config: https://syzkaller.appspot.com/x/.config?x=5b9537cd00be479e
> dashboard link: https://syzkaller.appspot.com/bug?extid=3195ed1f3a2ab8bea49a
> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/ebe2f3933faf/disk-22a40d14.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/7227032da0fe/vmlinux-22a40d14.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/a330dc1e107b/bzImage-22a40d14.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+3195ed...@syzkaller.appspotmail.com
Double-checked locking in eventpoll_release_file() should prevent NULL
<syzbot+3195ed...@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 22a40d14b572 Linux 6.10-rc6
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=10f94dae980000
> kernel config: https://syzkaller.appspot.com/x/.config?x=5b9537cd00be479e
> dashboard link: https://syzkaller.appspot.com/bug?extid=3195ed1f3a2ab8bea49a
> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/ebe2f3933faf/disk-22a40d14.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/7227032da0fe/vmlinux-22a40d14.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/a330dc1e107b/bzImage-22a40d14.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+3195ed...@syzkaller.appspotmail.com
derefs in eventpoll_release_file(), right? If so, it's probably
benign-ish.
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Christian Brauner
Jul 5, 2024, 6:34:34 AM (2 days ago) Jul 5
to Dmitry Vyukov, syzbot, ja...@suse.cz, linux-...@vger.kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com, vi...@zeniv.linux.org.uk
On Thu, Jul 04, 2024 at 04:40:40PM GMT, Dmitry Vyukov wrote:
> On Thu, 4 Jul 2024 at 16:38, syzbot
> <syzbot+3195ed...@syzkaller.appspotmail.com> wrote:
> >
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit: 22a40d14b572 Linux 6.10-rc6
> > git tree: upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=10f94dae980000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=5b9537cd00be479e
> > dashboard link: https://syzkaller.appspot.com/bug?extid=3195ed1f3a2ab8bea49a
> > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> >
> > Unfortunately, I don't have any reproducer for this issue yet.
> >
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/ebe2f3933faf/disk-22a40d14.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/7227032da0fe/vmlinux-22a40d14.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/a330dc1e107b/bzImage-22a40d14.xz
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+3195ed...@syzkaller.appspotmail.com
>
>
> Double-checked locking in eventpoll_release_file() should prevent NULL
> derefs in eventpoll_release_file(), right? If so, it's probably
> benign-ish.
Yes, see the comment to eventpoll_release(). I assume a READ_ONCE()
> On Thu, 4 Jul 2024 at 16:38, syzbot
> <syzbot+3195ed...@syzkaller.appspotmail.com> wrote:
> >
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit: 22a40d14b572 Linux 6.10-rc6
> > git tree: upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=10f94dae980000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=5b9537cd00be479e
> > dashboard link: https://syzkaller.appspot.com/bug?extid=3195ed1f3a2ab8bea49a
> > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> >
> > Unfortunately, I don't have any reproducer for this issue yet.
> >
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/ebe2f3933faf/disk-22a40d14.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/7227032da0fe/vmlinux-22a40d14.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/a330dc1e107b/bzImage-22a40d14.xz
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+3195ed...@syzkaller.appspotmail.com
>
>
> Double-checked locking in eventpoll_release_file() should prevent NULL
> derefs in eventpoll_release_file(), right? If so, it's probably
> benign-ish.
would be ok to add there so that race is annotated.
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