[moderation] [ext4?] KCSAN: data-race in data_push_tail / uuid_string (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: de2f378f2b77 Merge tag 'nfsd-6.12-4' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11e83e30580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e351f666e62e0b06
dashboard link: https://syzkaller.appspot.com/bug?extid=571ade47503c6ba10541
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [adilger...@dilger.ca linux...@vger.kernel.org linux-...@vger.kernel.org ty...@mit.edu]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/bf731037d3a8/disk-de2f378f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/208315e53eb0/vmlinux-de2f378f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/562fd699aa4a/bzImage-de2f378f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+571ade...@syzkaller.appspotmail.com

syz.0.2225[9651] is installing a program with bpf_probe_write_user helper that may corrupt user memory!
syz.0.2225[9651] is installing a program with bpf_probe_write_user helper that may corrupt user memory!
==================================================================
BUG: KCSAN: data-race in data_push_tail / uuid_string

write to 0xffffffff88bb5d71 of 1 bytes by task 3318 on cpu 0:
string_nocheck lib/vsprintf.c:650 [inline]
uuid_string+0x435/0x4b0 lib/vsprintf.c:1731
pointer+0x3ee/0xd20 lib/vsprintf.c:2432
vsnprintf+0x861/0xe30 lib/vsprintf.c:2807
va_format lib/vsprintf.c:1683 [inline]
pointer+0x8a1/0xd20 lib/vsprintf.c:2434
vsnprintf+0x861/0xe30 lib/vsprintf.c:2807
vscnprintf+0x42/0x90 lib/vsprintf.c:2909
printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2197
vprintk_store+0x570/0x810 kernel/printk/printk.c:2311
vprintk_emit+0x15e/0x680 kernel/printk/printk.c:2383
vprintk_default+0x26/0x30 kernel/printk/printk.c:2422
vprintk+0x75/0x80 kernel/printk/printk_safe.c:68
_printk+0x7a/0xa0 kernel/printk/printk.c:2432
__ext4_msg+0x18e/0x1a0 fs/ext4/super.c:991
ext4_put_super+0x91/0x840 fs/ext4/super.c:1296
generic_shutdown_super+0xe5/0x220 fs/super.c:642
kill_block_super+0x2a/0x70 fs/super.c:1710
ext4_kill_sb+0x44/0x80 fs/ext4/super.c:7320
deactivate_locked_super+0x7d/0x1c0 fs/super.c:473
deactivate_super+0x9f/0xb0 fs/super.c:506
cleanup_mnt+0x268/0x2e0 fs/namespace.c:1373
__cleanup_mnt+0x19/0x20 fs/namespace.c:1380
task_work_run+0x13a/0x1a0 kernel/task_work.c:239
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 0xffffffff88bb5d70 of 8 bytes by task 9651 on cpu 1:
data_make_reusable kernel/printk/printk_ringbuffer.c:594 [inline]
data_push_tail+0x102/0x430 kernel/printk/printk_ringbuffer.c:679
data_alloc+0xbe/0x2c0 kernel/printk/printk_ringbuffer.c:1054
prb_reserve+0x85e/0xb60 kernel/printk/printk_ringbuffer.c:1669
vprintk_store+0x53f/0x810 kernel/printk/printk.c:2301
vprintk_emit+0x15e/0x680 kernel/printk/printk.c:2383
vprintk_default+0x26/0x30 kernel/printk/printk.c:2422
vprintk+0x75/0x80 kernel/printk/printk_safe.c:68
_printk+0x7a/0xa0 kernel/printk/printk.c:2432
bpf_get_probe_write_proto+0x8b/0x90 kernel/trace/bpf_trace.c:365
bpf_tracing_func_proto+0x596/0x790 kernel/trace/bpf_trace.c:1466
raw_tp_prog_func_proto+0x65/0xc0 kernel/trace/bpf_trace.c:1938
get_helper_proto kernel/bpf/verifier.c:10421 [inline]
check_helper_call+0x131/0x3d30 kernel/bpf/verifier.c:10441
do_check+0x4c42/0x7310 kernel/bpf/verifier.c:18526
do_check_common+0xc34/0x1160 kernel/bpf/verifier.c:21615
do_check_main kernel/bpf/verifier.c:21706 [inline]
bpf_check+0xa7de/0xcbf0 kernel/bpf/verifier.c:22418
bpf_prog_load+0xed4/0x1070 kernel/bpf/syscall.c:2846
__sys_bpf+0x463/0x7a0 kernel/bpf/syscall.c:5653
__do_sys_bpf kernel/bpf/syscall.c:5760 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5758 [inline]
__x64_sys_bpf+0x43/0x50 kernel/bpf/syscall.c:5758
x64_sys_call+0x2625/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:322
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000ffffe9ff -> 0x00000000ffffe920

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 9651 Comm: syz.0.2225 Not tainted 6.12.0-rc6-syzkaller-00279-gde2f378f2b77 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================
syz.0.2225[9651] is installing a program with bpf_probe_write_user helper that may corrupt user memory!
syz.0.2225 (9651) used greatest stack depth: 9080 bytes left


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.