* [syzbot] [kernel?] KCSAN: data-race in kobject_put / kobject_uevent_env (2)
@ 2024-07-18 8:55 syzbot
2024-07-18 10:38 ` Marco Elver
0 siblings, 1 reply; 4+ messages in thread
From: syzbot @ 2024-07-18 8:55 UTC (permalink / raw)
To: gregkh, linux-kernel, rafael, syzkaller-bugs
Hello,
syzbot found the following issue on:
HEAD commit: d67978318827 Merge tag 'x86_cpu_for_v6.11_rc1' of git://gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11af145e980000
kernel config: https://syzkaller.appspot.com/x/.config?x=ca8f4e92a17047ec
dashboard link: https://syzkaller.appspot.com/bug?extid=0ac8e4da6d5cfcc7743e
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/1f219d0a9994/disk-d6797831.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/91aed26b830f/vmlinux-d6797831.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c7e753e56950/bzImage-d6797831.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0ac8e4da6d5cfcc7743e@syzkaller.appspotmail.com
llcp: llcp_sock_recvmsg: Recv datagram failed state 3 -6 0
==================================================================
BUG: KCSAN: data-race in kobject_put / kobject_uevent_env
read-write to 0xffff888139ddec54 of 1 bytes by task 22621 on cpu 0:
kobject_uevent_env+0x4e/0x550 lib/kobject_uevent.c:476
kobject_uevent+0x1c/0x30 lib/kobject_uevent.c:641
device_del+0x6fa/0x780 drivers/base/core.c:3886
nfc_unregister_device+0x114/0x130 net/nfc/core.c:1183
nci_unregister_device+0x14c/0x160 net/nfc/nci/core.c:1312
virtual_ncidev_close+0x30/0x50 drivers/nfc/virtual_ncidev.c:172
__fput+0x192/0x6f0 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 0xffff888139ddec54 of 1 bytes by task 22615 on cpu 1:
kobject_put+0x25/0x180 lib/kobject.c:733
put_device+0x1f/0x30 drivers/base/core.c:3787
nfc_put_device net/nfc/nfc.h:103 [inline]
nfc_llcp_local_put+0x87/0xb0 net/nfc/llcp_core.c:196
nfc_llcp_sock_free net/nfc/llcp_sock.c:1021 [inline]
llcp_sock_destruct+0x14d/0x1a0 net/nfc/llcp_sock.c:966
__sk_destruct+0x3d/0x440 net/core/sock.c:2175
sk_destruct net/core/sock.c:2223 [inline]
__sk_free+0x284/0x2d0 net/core/sock.c:2234
sk_free+0x39/0x70 net/core/sock.c:2245
sock_put include/net/sock.h:1879 [inline]
llcp_sock_release+0x38f/0x3d0 net/nfc/llcp_sock.c:646
__sock_release net/socket.c:659 [inline]
sock_close+0x68/0x150 net/socket.c:1421
__fput+0x192/0x6f0 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
value changed: 0x07 -> 0x0d
Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 22615 Comm: syz.0.6322 Tainted: G W 6.10.0-syzkaller-01155-gd67978318827 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
==================================================================
---
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See https://goo.gl/tpsmEJ for more information about syzbot.
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If you want to undo deduplication, reply with:
#syz undup
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [syzbot] [kernel?] KCSAN: data-race in kobject_put / kobject_uevent_env (2)
2024-07-18 8:55 [syzbot] [kernel?] KCSAN: data-race in kobject_put / kobject_uevent_env (2) syzbot
@ 2024-07-18 10:38 ` Marco Elver
2024-07-18 11:09 ` Greg KH
0 siblings, 1 reply; 4+ messages in thread
From: Marco Elver @ 2024-07-18 10:38 UTC (permalink / raw)
To: syzbot; +Cc: gregkh, linux-kernel, rafael, syzkaller-bugs
On Thu, 18 Jul 2024 at 10:55, syzbot
<syzbot+0ac8e4da6d5cfcc7743e@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: d67978318827 Merge tag 'x86_cpu_for_v6.11_rc1' of git://gi..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=11af145e980000
> kernel config: https://syzkaller.appspot.com/x/.config?x=ca8f4e92a17047ec
> dashboard link: https://syzkaller.appspot.com/bug?extid=0ac8e4da6d5cfcc7743e
> 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/1f219d0a9994/disk-d6797831.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/91aed26b830f/vmlinux-d6797831.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/c7e753e56950/bzImage-d6797831.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+0ac8e4da6d5cfcc7743e@syzkaller.appspotmail.com
>
> llcp: llcp_sock_recvmsg: Recv datagram failed state 3 -6 0
> ==================================================================
> BUG: KCSAN: data-race in kobject_put / kobject_uevent_env
>
> read-write to 0xffff888139ddec54 of 1 bytes by task 22621 on cpu 0:
> kobject_uevent_env+0x4e/0x550 lib/kobject_uevent.c:476
> kobject_uevent+0x1c/0x30 lib/kobject_uevent.c:641
> device_del+0x6fa/0x780 drivers/base/core.c:3886
> nfc_unregister_device+0x114/0x130 net/nfc/core.c:1183
> nci_unregister_device+0x14c/0x160 net/nfc/nci/core.c:1312
> virtual_ncidev_close+0x30/0x50 drivers/nfc/virtual_ncidev.c:172
> __fput+0x192/0x6f0 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 0xffff888139ddec54 of 1 bytes by task 22615 on cpu 1:
> kobject_put+0x25/0x180 lib/kobject.c:733
> put_device+0x1f/0x30 drivers/base/core.c:3787
> nfc_put_device net/nfc/nfc.h:103 [inline]
> nfc_llcp_local_put+0x87/0xb0 net/nfc/llcp_core.c:196
> nfc_llcp_sock_free net/nfc/llcp_sock.c:1021 [inline]
> llcp_sock_destruct+0x14d/0x1a0 net/nfc/llcp_sock.c:966
> __sk_destruct+0x3d/0x440 net/core/sock.c:2175
> sk_destruct net/core/sock.c:2223 [inline]
> __sk_free+0x284/0x2d0 net/core/sock.c:2234
> sk_free+0x39/0x70 net/core/sock.c:2245
> sock_put include/net/sock.h:1879 [inline]
> llcp_sock_release+0x38f/0x3d0 net/nfc/llcp_sock.c:646
> __sock_release net/socket.c:659 [inline]
> sock_close+0x68/0x150 net/socket.c:1421
> __fput+0x192/0x6f0 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
>
> value changed: 0x07 -> 0x0d
>
> Reported by Kernel Concurrency Sanitizer on:
> CPU: 1 PID: 22615 Comm: syz.0.6322 Tainted: G W 6.10.0-syzkaller-01155-gd67978318827 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
> ==================================================================
The two racing accesses here (on bitfield variables
kobj->state_remove_uevent_sent, kobj->state_initialized) are in the
same bitfield. There's no guarantee (by the compiler) that while the
bitfield is being updated the bit at kobj->state_initialized will
remain non-zero, and therefore the WARN in kobject_put() could be
triggered. This appears benign, unless of course someone set
panic_on_warn.
More generally, if the bitfield is updated concurrently, it's very
likely that one of the updates would be lost.
Just my initial observation.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [syzbot] [kernel?] KCSAN: data-race in kobject_put / kobject_uevent_env (2)
2024-07-18 10:38 ` Marco Elver
@ 2024-07-18 11:09 ` Greg KH
2024-07-18 13:34 ` Tetsuo Handa
0 siblings, 1 reply; 4+ messages in thread
From: Greg KH @ 2024-07-18 11:09 UTC (permalink / raw)
To: Marco Elver; +Cc: syzbot, linux-kernel, rafael, syzkaller-bugs
On Thu, Jul 18, 2024 at 12:38:05PM +0200, Marco Elver wrote:
> On Thu, 18 Jul 2024 at 10:55, syzbot
> <syzbot+0ac8e4da6d5cfcc7743e@syzkaller.appspotmail.com> wrote:
> >
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit: d67978318827 Merge tag 'x86_cpu_for_v6.11_rc1' of git://gi..
> > git tree: upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=11af145e980000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=ca8f4e92a17047ec
> > dashboard link: https://syzkaller.appspot.com/bug?extid=0ac8e4da6d5cfcc7743e
> > 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/1f219d0a9994/disk-d6797831.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/91aed26b830f/vmlinux-d6797831.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/c7e753e56950/bzImage-d6797831.xz
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+0ac8e4da6d5cfcc7743e@syzkaller.appspotmail.com
> >
> > llcp: llcp_sock_recvmsg: Recv datagram failed state 3 -6 0
> > ==================================================================
> > BUG: KCSAN: data-race in kobject_put / kobject_uevent_env
> >
> > read-write to 0xffff888139ddec54 of 1 bytes by task 22621 on cpu 0:
> > kobject_uevent_env+0x4e/0x550 lib/kobject_uevent.c:476
> > kobject_uevent+0x1c/0x30 lib/kobject_uevent.c:641
> > device_del+0x6fa/0x780 drivers/base/core.c:3886
> > nfc_unregister_device+0x114/0x130 net/nfc/core.c:1183
> > nci_unregister_device+0x14c/0x160 net/nfc/nci/core.c:1312
> > virtual_ncidev_close+0x30/0x50 drivers/nfc/virtual_ncidev.c:172
> > __fput+0x192/0x6f0 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 0xffff888139ddec54 of 1 bytes by task 22615 on cpu 1:
> > kobject_put+0x25/0x180 lib/kobject.c:733
> > put_device+0x1f/0x30 drivers/base/core.c:3787
> > nfc_put_device net/nfc/nfc.h:103 [inline]
> > nfc_llcp_local_put+0x87/0xb0 net/nfc/llcp_core.c:196
> > nfc_llcp_sock_free net/nfc/llcp_sock.c:1021 [inline]
> > llcp_sock_destruct+0x14d/0x1a0 net/nfc/llcp_sock.c:966
> > __sk_destruct+0x3d/0x440 net/core/sock.c:2175
> > sk_destruct net/core/sock.c:2223 [inline]
> > __sk_free+0x284/0x2d0 net/core/sock.c:2234
> > sk_free+0x39/0x70 net/core/sock.c:2245
> > sock_put include/net/sock.h:1879 [inline]
> > llcp_sock_release+0x38f/0x3d0 net/nfc/llcp_sock.c:646
> > __sock_release net/socket.c:659 [inline]
> > sock_close+0x68/0x150 net/socket.c:1421
> > __fput+0x192/0x6f0 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
> >
> > value changed: 0x07 -> 0x0d
> >
> > Reported by Kernel Concurrency Sanitizer on:
> > CPU: 1 PID: 22615 Comm: syz.0.6322 Tainted: G W 6.10.0-syzkaller-01155-gd67978318827 #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
> > ==================================================================
>
> The two racing accesses here (on bitfield variables
> kobj->state_remove_uevent_sent, kobj->state_initialized) are in the
> same bitfield. There's no guarantee (by the compiler) that while the
> bitfield is being updated the bit at kobj->state_initialized will
> remain non-zero, and therefore the WARN in kobject_put() could be
> triggered. This appears benign, unless of course someone set
> panic_on_warn.
>
> More generally, if the bitfield is updated concurrently, it's very
> likely that one of the updates would be lost.
>
> Just my initial observation.
Thanks for the review, I'll try to carve out some time next week to
knock up a patch for this...
greg k-h
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [syzbot] [kernel?] KCSAN: data-race in kobject_put / kobject_uevent_env (2)
2024-07-18 11:09 ` Greg KH
@ 2024-07-18 13:34 ` Tetsuo Handa
0 siblings, 0 replies; 4+ messages in thread
From: Tetsuo Handa @ 2024-07-18 13:34 UTC (permalink / raw)
To: Greg KH, Marco Elver; +Cc: syzbot, linux-kernel, rafael, syzkaller-bugs
On 2024/07/18 20:09, Greg KH wrote:
> On Thu, Jul 18, 2024 at 12:38:05PM +0200, Marco Elver wrote:
>> The two racing accesses here (on bitfield variables
>> kobj->state_remove_uevent_sent, kobj->state_initialized) are in the
>> same bitfield. There's no guarantee (by the compiler) that while the
>> bitfield is being updated the bit at kobj->state_initialized will
>> remain non-zero, and therefore the WARN in kobject_put() could be
>> triggered. This appears benign, unless of course someone set
>> panic_on_warn.
>>
>> More generally, if the bitfield is updated concurrently, it's very
>> likely that one of the updates would be lost.
>>
>> Just my initial observation.
>
> Thanks for the review, I'll try to carve out some time next week to
> knock up a patch for this...
Unless it is proven that these
unsigned int state_initialized:1;
unsigned int state_in_sysfs:1;
unsigned int state_add_uevent_sent:1;
unsigned int state_remove_uevent_sent:1;
unsigned int uevent_suppress:1;
fields are never modified concurrently, just marking this "unsigned int" as
__data_racy is wrong.
When we hit unprotected bitmask modification bug at
https://lkml.kernel.org/r/201409192053.IHJ35462.JLOMOSOFFVtQFH@I-love.SAKURA.ne.jp ,
we fixed the race by converting to test_bit()/set_bit()/clear_bit().
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2024-07-18 13:34 UTC | newest]
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2024-07-18 8:55 [syzbot] [kernel?] KCSAN: data-race in kobject_put / kobject_uevent_env (2) syzbot
2024-07-18 10:38 ` Marco Elver
2024-07-18 11:09 ` Greg KH
2024-07-18 13:34 ` Tetsuo Handa
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