syzbot


KCSAN: data-race in redirty_tail_locked / vfs_fsync_range

Status: moderation: reported on 2024/05/19 01:00
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+1d932cad9edef9ea852b@syzkaller.appspotmail.com
First crash: 27d, last: 27d

Sample crash report:
==================================================================
BUG: KCSAN: data-race in redirty_tail_locked / vfs_fsync_range

read-write to 0xffff8881080ee1b0 of 8 bytes by task 3599 on cpu 1:
 redirty_tail_locked+0x56/0x270 fs/fs-writeback.c:1346
 writeback_single_inode+0x1ea/0x4a0 fs/fs-writeback.c:1792
 sync_inode_metadata+0x5c/0x90 fs/fs-writeback.c:2842
 generic_buffers_fsync_noflush+0xe4/0x130 fs/buffer.c:612
 ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
 ext4_sync_file+0x20b/0x6c0 fs/ext4/fsync.c:151
 vfs_fsync_range+0x122/0x140 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2811 [inline]
 ext4_buffered_write_iter+0x338/0x380 fs/ext4/file.c:305
 ext4_file_write_iter+0x29f/0xe30
 call_write_iter include/linux/fs.h:2120 [inline]
 iter_file_splice_write+0x5e6/0x970 fs/splice.c:743
 do_splice_from fs/splice.c:941 [inline]
 direct_splice_actor+0x16c/0x2c0 fs/splice.c:1164
 splice_direct_to_actor+0x305/0x670 fs/splice.c:1108
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x3b9/0x970 fs/read_write.c:1295
 __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+0x2c67/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:41
 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

read to 0xffff8881080ee1b0 of 8 bytes by task 3606 on cpu 0:
 vfs_fsync_range+0xa6/0x140 fs/sync.c:186
 generic_write_sync include/linux/fs.h:2811 [inline]
 ext4_buffered_write_iter+0x338/0x380 fs/ext4/file.c:305
 ext4_file_write_iter+0x29f/0xe30
 call_write_iter include/linux/fs.h:2120 [inline]
 iter_file_splice_write+0x5e6/0x970 fs/splice.c:743
 do_splice_from fs/splice.c:941 [inline]
 direct_splice_actor+0x16c/0x2c0 fs/splice.c:1164
 splice_direct_to_actor+0x305/0x670 fs/splice.c:1108
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x3b9/0x970 fs/read_write.c:1295
 __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+0x2c67/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:41
 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: 0x0000000000000087 -> 0x0000000000000080

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3606 Comm: syz-executor.1 Not tainted 6.9.0-syzkaller-08544-g4b377b4868ef #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/05/19 01:00 upstream 4b377b4868ef c0f1611a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in redirty_tail_locked / vfs_fsync_range
* Struck through repros no longer work on HEAD.