[moderation] [audit?] KCSAN: data-race in data_push_tail / number (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 89be9a83ccf1 Linux 6.16-rc7
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14512f22580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c0dd0a92e88efc24
dashboard link: https://syzkaller.appspot.com/bug?extid=7b1cbf8ab9b0340d009e
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
CC: [au...@vger.kernel.org epa...@redhat.com linux-...@vger.kernel.org pa...@paul-moore.com]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0ddf56b16465/disk-89be9a83.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d352fc68f5dd/vmlinux-89be9a83.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2cfbbbe4e4f4/bzImage-89be9a83.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7b1cbf...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in data_push_tail / number

write to 0xffffffff88e52428 of 1 bytes by task 30 on cpu 0:
number+0x8d6/0xab0 lib/vsprintf.c:558
vsnprintf+0x691/0x890 lib/vsprintf.c:2838
vscnprintf+0x41/0x90 lib/vsprintf.c:2939
printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2216
vprintk_store+0x599/0x860 kernel/printk/printk.c:2336
vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426
vprintk_default+0x26/0x30 kernel/printk/printk.c:2465
vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
_printk+0x79/0xa0 kernel/printk/printk.c:2475
kauditd_printk_skb kernel/audit.c:546 [inline]
kauditd_hold_skb+0x1b1/0x1c0 kernel/audit.c:581
kauditd_send_queue+0x270/0x2c0 kernel/audit.c:766
kauditd_thread+0x421/0x630 kernel/audit.c:890
kthread+0x489/0x510 kernel/kthread.c:464
ret_from_fork+0xda/0x150 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffffffff88e52428 of 8 bytes by task 29069 on cpu 1:
data_make_reusable kernel/printk/printk_ringbuffer.c:594 [inline]
data_push_tail+0xfd/0x420 kernel/printk/printk_ringbuffer.c:679
data_alloc+0xbf/0x2b0 kernel/printk/printk_ringbuffer.c:1054
prb_reserve+0x808/0xaf0 kernel/printk/printk_ringbuffer.c:1669
vprintk_store+0x56d/0x860 kernel/printk/printk.c:2326
vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426
vprintk_default+0x26/0x30 kernel/printk/printk.c:2465
vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
_printk+0x79/0xa0 kernel/printk/printk.c:2475
set_capacity_and_notify+0x14c/0x1f0 block/genhd.c:93
loop_set_size+0x2e/0x70 drivers/block/loop.c:210
loop_configure+0x8d3/0xa50 drivers/block/loop.c:1067
lo_ioctl+0x559/0x15d0 drivers/block/loop.c:-1
blkdev_ioctl+0x34f/0x440 block/ioctl.c:704
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:907 [inline]
__se_sys_ioctl+0xcb/0x140 fs/ioctl.c:893
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:893
x64_sys_call+0x19a8/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000100000d70 -> 0x3128746964756120

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 29069 Comm: syz.8.6224 Not tainted 6.16.0-rc7-syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================
vfat: Unknown parameter '0x000000000000041e18446744073709551615'
netlink: 4 bytes leftover after parsing attributes in process `syz.8.6224'.


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[syzbot]

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