[moderation] [fs?] KCSAN: data-race in do_sendfile / do_sendfile (8)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 66e55ff12e73 Merge tag 'for-6.10-rc5-tag' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=128d1ba6980000
kernel config: https://syzkaller.appspot.com/x/.config?x=7e87b541dc1fc960
dashboard link: https://syzkaller.appspot.com/bug?extid=b53ccd1d8d8f06f6c8b8
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [bra...@kernel.org ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/bf21f8e58486/disk-66e55ff1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/480012b06f5d/vmlinux-66e55ff1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2c8c3b8aab4c/bzImage-66e55ff1.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b53ccd...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in do_sendfile / do_sendfile

write to 0xffff888112770d40 of 8 bytes by task 25265 on cpu 0:
do_sendfile+0x781/0x960
__do_sys_sendfile64 fs/read_write.c:1362 [inline]
__se_sys_sendfile64 fs/read_write.c:1348 [inline]
__x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
x64_sys_call+0x2c9f/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:41
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

write to 0xffff888112770d40 of 8 bytes by task 25268 on cpu 1:
do_sendfile+0x753/0x960 fs/read_write.c:1309
__do_sys_sendfile64 fs/read_write.c:1362 [inline]
__se_sys_sendfile64 fs/read_write.c:1348 [inline]
__x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
x64_sys_call+0x2c9f/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:41
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: 0x0000000000000000 -> 0x00000000003b0000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 25268 Comm: syz.2.6900 Not tainted 6.10.0-rc5-syzkaller-00155-g66e55ff12e73 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
==================================================================


---
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