[moderation] [fs?] KCSAN: data-race in do_sendfile / ksys_write (15)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ffd2cb6b718e Merge tag 'block-6.8-2024-02-22' of git://git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10c80be8180000
kernel config: https://syzkaller.appspot.com/x/.config?x=7507056e4ee79a
dashboard link: https://syzkaller.appspot.com/bug?extid=cbf88f510837a35e8b6e
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/39381abd5225/disk-ffd2cb6b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ff41c10035b2/vmlinux-ffd2cb6b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5ae87ad501b6/bzImage-ffd2cb6b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cbf88f...@syzkaller.appspotmail.com

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

write to 0xffff8881883a1d40 of 8 bytes by task 9343 on cpu 0:
do_sendfile+0x758/0x960 fs/read_write.c:1309
__do_sys_sendfile64 fs/read_write.c:1356 [inline]
__se_sys_sendfile64 fs/read_write.c:1348 [inline]
__x64_sys_sendfile64+0xbd/0x150 fs/read_write.c:1348
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

write to 0xffff8881883a1d40 of 8 bytes by task 9337 on cpu 1:
ksys_write+0x11e/0x1a0 fs/read_write.c:645
__do_sys_write fs/read_write.c:655 [inline]
__se_sys_write fs/read_write.c:652 [inline]
__x64_sys_write+0x42/0x50 fs/read_write.c:652
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 -> 0x00000000000000bf

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 9337 Comm: syz-executor.1 Not tainted 6.8.0-rc5-syzkaller-00163-gffd2cb6b718e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
==================================================================


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[syzbot]

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