[moderation] [block?] KCSAN: data-race in data_push_tail / vsnprintf (9)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: bb066fe812d6 Merge tag 'pci-v6.14-fixes-2' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=155121b0580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9e757e3762bd630b
dashboard link: https://syzkaller.appspot.com/bug?extid=504460beb7923d347fba
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [ax...@kernel.dk linux...@vger.kernel.org linux-...@vger.kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/96c2fa324092/disk-bb066fe8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d0c48f9198dc/vmlinux-bb066fe8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a9ae4ace7c1c/bzImage-bb066fe8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+504460...@syzkaller.appspotmail.com

truncated
loop0: p225 size 108986237 extends beyond EOD, truncated
loop0: p226 size 108986237 extends beyond EOD,
==================================================================
BUG: KCSAN: data-race in data_push_tail / vsnprintf

write to 0xffffffff88bf7090 of 1 bytes by task 5529 on cpu 0:
vsnprintf+0x844/0x890
vscnprintf+0x42/0x90 lib/vsprintf.c:2908
printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2216
vprintk_store+0x589/0x870 kernel/printk/printk.c:2336
vprintk_emit+0x15e/0x680 kernel/printk/printk.c:2408
vprintk_default+0x26/0x30 kernel/printk/printk.c:2447
vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
_printk+0x7a/0xa0 kernel/printk/printk.c:2457
blk_add_partition block/partitions/core.c:549 [inline]
blk_add_partitions block/partitions/core.c:633 [inline]
bdev_disk_changed+0x87f/0xb90 block/partitions/core.c:693
loop_reread_partitions drivers/block/loop.c:537 [inline]
loop_set_status+0x37e/0x590 drivers/block/loop.c:1305
lo_ioctl+0x81b/0x14d0
blkdev_ioctl+0x359/0x450 block/ioctl.c:693
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl+0xc9/0x140 fs/ioctl.c:892
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:892
x64_sys_call+0x1690/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:17
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

read to 0xffffffff88bf7090 of 8 bytes by task 5461 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+0x558/0x870 kernel/printk/printk.c:2326
vprintk_emit+0x15e/0x680 kernel/printk/printk.c:2408
vprintk_default+0x26/0x30 kernel/printk/printk.c:2447
vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
_printk+0x7a/0xa0 kernel/printk/printk.c:2457
blk_add_partition block/partitions/core.c:549 [inline]
blk_add_partitions block/partitions/core.c:633 [inline]
bdev_disk_changed+0x87f/0xb90 block/partitions/core.c:693
loop_reread_partitions drivers/block/loop.c:537 [inline]
loop_set_status+0x37e/0x590 drivers/block/loop.c:1305
lo_ioctl+0x81b/0x14d0
blkdev_ioctl+0x359/0x450 block/ioctl.c:693
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl+0xc9/0x140 fs/ioctl.c:892
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:892
x64_sys_call+0x1690/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:17
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: 0x00000000ffffec35 -> 0x6564657461636e75

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5461 Comm: syz.0.704 Not tainted 6.14.0-rc1-syzkaller-00081-gbb066fe812d6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
==================================================================
truncated
loop0: p227 size 108986237 extends beyond EOD,
truncated
loop0: p228 size 108986237 extends beyond EOD, truncated
loop0: p229 size 108986237 extends beyond EOD, truncated
loop0: p230 size 108986237 extends beyond EOD, truncated
loop0: p231 size 108986237 extends beyond EOD, truncated
loop0: p232 size 108986237 extends beyond EOD, truncated
loop0: p233 size 108986237 extends beyond EOD, truncated
loop0: p234 size 108986237 extends beyond EOD,
truncated
loop0: p235 size 108986237 extends beyond EOD,
truncated
loop0: p236 size 108986237 extends beyond EOD,
truncated
loop0: p237 size 108986237 extends beyond EOD,
truncated
loop0: p238 size 108986237 extends beyond EOD,
truncated
loop0: p239 size 108986237 extends beyond EOD,
truncated
loop0: p240 size 108986237 extends beyond EOD,
truncated
loop0: p241 size 108986237 extends beyond EOD,
truncated
loop0: p242 size 108986237 extends beyond EOD,
truncated
loop0: p243 size 108986237 extends beyond EOD,
truncated
loop0: p244 size 108986237 extends beyond EOD,
truncated
loop0: p245 size 108986237 extends beyond EOD,
truncated
loop0: p246 size 108986237 extends beyond EOD,
truncated
loop0: p247 size 108986237 extends beyond EOD,
truncated
loop0: p248 size 108986237 extends beyond EOD,
truncated
loop0: p249 size 108986237 extends beyond EOD,
truncated
loop0: p250 size 108986237 extends beyond EOD,
truncated
loop0: p251 size 108986237 extends beyond EOD,
truncated
loop0: p252 size 108986237 extends beyond EOD,
truncated
loop0: p253 size 108986237 extends beyond EOD,
truncated
loop0: p254 size 108986237 extends beyond EOD,
truncated
loop0: p255 size 108986237 extends beyond EOD,
truncated


---
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