syzbot


KCSAN: data-race in ext4_setattr / mpage_process_page_bufs (3)

Status: closed as invalid on 2022/05/13 11:20
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 205d, last: 205d
similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in ext4_setattr / mpage_process_page_bufs (2) 265 347d 803d 0/24 auto-closed as invalid on 2022/01/24 23:19
upstream KCSAN: data-race in ext4_setattr / mpage_process_page_bufs 35 903d 1126d 0/24 closed as invalid on 2020/06/18 14:24

Sample crash report:
==================================================================
BUG: KCSAN: data-race in ext4_setattr / mpage_process_page_bufs

write to 0xffff88813869e278 of 8 bytes by task 19563 on cpu 1:
 i_size_write include/linux/fs.h:878 [inline]
 ext4_setattr+0xcf4/0xdf0 fs/ext4/inode.c:5482
 notify_change+0x9c3/0xa30 fs/attr.c:410
 do_truncate+0xf7/0x140 fs/open.c:65
 handle_truncate fs/namei.c:3132 [inline]
 do_open fs/namei.c:3480 [inline]
 path_openat+0x1834/0x1b30 fs/namei.c:3609
 do_filp_open+0x105/0x220 fs/namei.c:3636
 do_sys_openat2+0xb5/0x2a0 fs/open.c:1213
 do_sys_open fs/open.c:1229 [inline]
 __do_sys_openat fs/open.c:1245 [inline]
 __se_sys_openat fs/open.c:1240 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1240
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88813869e278 of 8 bytes by task 19559 on cpu 0:
 i_size_read include/linux/fs.h:856 [inline]
 mpage_process_page_bufs+0x34/0x530 fs/ext4/inode.c:2182
 mpage_prepare_extent_to_map+0x5b7/0xa50 fs/ext4/inode.c:2630
 ext4_writepages+0x9b8/0x1d00 fs/ext4/inode.c:2802
 do_writepages+0x1db/0x350 mm/page-writeback.c:2352
 filemap_fdatawrite_wbc+0xd6/0xf0 mm/filemap.c:388
 __filemap_fdatawrite_range mm/filemap.c:421 [inline]
 __filemap_fdatawrite mm/filemap.c:427 [inline]
 filemap_flush+0x93/0xc0 mm/filemap.c:454
 ext4_alloc_da_blocks+0x47/0x100 fs/ext4/inode.c:3112
 ext4_release_file+0x5b/0x1d0 fs/ext4/file.c:143
 __fput+0x292/0x510 fs/file_table.c:317
 ____fput+0x11/0x20 fs/file_table.c:350
 task_work_run+0x8e/0x110 kernel/task_work.c:164
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0x124/0x130 kernel/entry/common.c:169
 exit_to_user_mode_prepare kernel/entry/common.c:201 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
 syscall_exit_to_user_mode+0x6a/0x90 kernel/entry/common.c:294
 do_syscall_64+0x37/0x70 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000400086 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 19559 Comm: syz-executor.5 Not tainted 5.18.0-rc6-syzkaller-00009-gfeb9c5e19e91 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-upstream-kcsan-gce 2022/05/12 08:13 upstream feb9c5e19e91 beb0b407 .config log report info KCSAN: data-race in ext4_setattr / mpage_process_page_bufs
* Struck through repros no longer work on HEAD.