[moderation] [audit?] KCSAN: data-race in memchr / string (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 448b3fe5a0ea Merge tag 'hwmon-for-v6.9-rc8' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1125bfdf180000
kernel config: https://syzkaller.appspot.com/x/.config?x=168fab99759dff68
dashboard link: https://syzkaller.appspot.com/bug?extid=d0a30aa354a1e3687368
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
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/2a9bd6ab04dd/disk-448b3fe5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3d2ac1ed19d2/vmlinux-448b3fe5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0ab4074112ed/bzImage-448b3fe5.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d0a30a...@syzkaller.appspotmail.com

BUG: KCSAN: data-race in memchr / string

write to 0xffffffff883bdc0b of 1 bytes by task 28 on cpu 0:
string_nocheck lib/vsprintf.c:650 [inline]
string+0x16c/0x210 lib/vsprintf.c:728
vsnprintf+0xa09/0xe30 lib/vsprintf.c:2824
vscnprintf+0x42/0x90 lib/vsprintf.c:2930
printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2165
vprintk_store+0x570/0x810 kernel/printk/printk.c:2279
vprintk_emit+0x10c/0x5e0 kernel/printk/printk.c:2329
vprintk_default+0x26/0x30 kernel/printk/printk.c:2363
vprintk+0x75/0x80 kernel/printk/printk_safe.c:45
_printk+0x7a/0xa0 kernel/printk/printk.c:2373
kauditd_printk_skb kernel/audit.c:546 [inline]
kauditd_hold_skb+0x1a1/0x1b0 kernel/audit.c:581
kauditd_send_queue+0x288/0x2e0 kernel/audit.c:766
kauditd_thread+0x42a/0x650 kernel/audit.c:890
kthread+0x1d1/0x210 kernel/kthread.c:388
ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read to 0xffffffff883bdc0b of 1 bytes by task 19576 on cpu 1:
memchr+0x2a/0x50 lib/string.c:791
count_lines kernel/printk/printk_ringbuffer.c:1797 [inline]
copy_data kernel/printk/printk_ringbuffer.c:1843 [inline]
prb_read kernel/printk/printk_ringbuffer.c:1936 [inline]
_prb_read_valid+0xa26/0xba0 kernel/printk/printk_ringbuffer.c:2113
prb_read_valid_info+0x67/0x90 kernel/printk/printk_ringbuffer.c:2216
find_first_fitting_seq+0x142/0x310 kernel/printk/printk.c:1519
syslog_print_all+0x11d/0x5a0 kernel/printk/printk.c:1670
do_syslog+0x41c/0x7d0 kernel/printk/printk.c:1748
__do_sys_syslog kernel/printk/printk.c:1826 [inline]
__se_sys_syslog kernel/printk/printk.c:1824 [inline]
__x64_sys_syslog+0x43/0x50 kernel/printk/printk.c:1824
x64_sys_call+0x2695/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:104
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x63 -> 0x65

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 19576 Comm: syz-executor.1 Not tainted 6.9.0-rc7-syzkaller-00117-g448b3fe5a0ea #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
==================================================================


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