[moderation] [block?] KCSAN: data-race in bdev_set_nr_sectors / blkdev_llseek (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 603c04e27c3e Merge tag 'parisc-for-6.8-rc6' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11aac58c180000
kernel config: https://syzkaller.appspot.com/x/.config?x=7507056e4ee79a
dashboard link: https://syzkaller.appspot.com/bug?extid=0d7b644aedafced2cab3
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/5d2e1735161f/disk-603c04e2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1581e5112b38/vmlinux-603c04e2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/10bbd2ece0b5/bzImage-603c04e2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0d7b64...@syzkaller.appspotmail.com

BUG: KCSAN: data-race in bdev_set_nr_sectors / blkdev_llseek

write to 0xffff888100630a30 of 8 bytes by task 4305 on cpu 1:
i_size_write include/linux/fs.h:934 [inline]
bdev_set_nr_sectors+0x42/0x70 block/bdev.c:427
set_capacity block/genhd.c:61 [inline]
set_capacity_and_notify+0x6e/0x170 block/genhd.c:74
loop_set_size+0x2e/0x70 drivers/block/loop.c:235
loop_configure+0xaf9/0xca0 drivers/block/loop.c:1096
lo_ioctl+0x682/0x12e0
blkdev_ioctl+0x375/0x460 block/ioctl.c:634
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xcf/0x140 fs/ioctl.c:857
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:857
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+0x63/0x6b

read to 0xffff888100630a30 of 8 bytes by task 901 on cpu 0:
i_size_read include/linux/fs.h:912 [inline]
blkdev_llseek+0x50/0x80 block/fops.c:533
vfs_llseek fs/read_write.c:289 [inline]
ksys_lseek fs/read_write.c:302 [inline]
__do_sys_lseek fs/read_write.c:313 [inline]
__se_sys_lseek fs/read_write.c:311 [inline]
__x64_sys_lseek+0xe9/0x150 fs/read_write.c:311
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+0x63/0x6b

value changed: 0x0000000000000000 -> 0x000000000005c000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 901 Comm: udevd Not tainted 6.8.0-rc5-syzkaller-00278-g603c04e27c3e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
==================================================================
I/O error, dev loop1, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
I/O error, dev loop1, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
I/O error, dev loop1, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
I/O error, dev loop1, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
blk_print_req_error: 2 callbacks suppressed
I/O error, dev loop1, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
I/O error, dev loop1, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
I/O error, dev loop1, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
I/O error, dev loop1, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
I/O error, dev loop1, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
I/O error, dev loop1, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0


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[syzbot]

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