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KCSAN: data-race in __d_instantiate / lookup_fast (7)

Status: upstream: reported on 2024/06/20 08:23
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+5757df85a1c108693de1@syzkaller.appspotmail.com
First crash: 23d, last: 23d
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [ext4?] KCSAN: data-race in __d_instantiate / lookup_fast (7) 0 (1) 2024/06/20 08:23
Similar bugs (6)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __d_instantiate / lookup_fast (6) ext4 53 61d 217d 0/27 auto-obsoleted due to no activity on 2024/06/16 23:52
upstream KCSAN: data-race in __d_instantiate / lookup_fast ext4 6 1538d 1663d 0/27 auto-closed as invalid on 2020/06/18 13:33
upstream KCSAN: data-race in __d_instantiate / lookup_fast (4) ext4 16 706d 822d 0/27 auto-closed as invalid on 2022/09/10 18:37
upstream KCSAN: data-race in __d_instantiate / lookup_fast (5) ext4 7 614d 667d 0/27 auto-obsoleted due to no activity on 2022/12/11 12:03
upstream KCSAN: data-race in __d_instantiate / lookup_fast (2) fs 1 1248d 1248d 0/27 auto-closed as invalid on 2021/03/18 02:49
upstream KCSAN: data-race in __d_instantiate / lookup_fast (3) ext4 1 1095d 1095d 0/27 auto-closed as invalid on 2021/08/17 22:04

Sample crash report:
==================================================================
BUG: KCSAN: data-race in __d_instantiate / lookup_fast

read-write to 0xffff8881207d1d80 of 4 bytes by task 25805 on cpu 1:
 __d_instantiate+0x2cd/0x3c0 fs/dcache.c:1855
 d_instantiate_new+0x5c/0xf0 fs/dcache.c:1899
 ext4_mkdir+0x5e6/0x740 fs/ext4/namei.c:3047
 vfs_mkdir+0x1f4/0x320 fs/namei.c:4131
 do_mkdirat+0x12f/0x2a0 fs/namei.c:4154
 __do_sys_mkdir fs/namei.c:4174 [inline]
 __se_sys_mkdir fs/namei.c:4172 [inline]
 __x64_sys_mkdir+0x44/0x50 fs/namei.c:4172
 x64_sys_call+0x10d4/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:84
 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

read to 0xffff8881207d1d80 of 4 bytes by task 25807 on cpu 0:
 d_revalidate fs/namei.c:860 [inline]
 lookup_fast+0xd9/0x2a0 fs/namei.c:1641
 walk_component fs/namei.c:2000 [inline]
 link_path_walk+0x403/0x810 fs/namei.c:2331
 path_lookupat+0x72/0x2b0 fs/namei.c:2492
 filename_lookup+0x127/0x300 fs/namei.c:2522
 user_path_at_empty+0x42/0x120 fs/namei.c:2929
 user_path_at include/linux/namei.h:58 [inline]
 path_setxattr+0x60/0x1a0 fs/xattr.c:666
 __do_sys_setxattr fs/xattr.c:687 [inline]
 __se_sys_setxattr fs/xattr.c:683 [inline]
 __x64_sys_setxattr+0x6d/0x80 fs/xattr.c:683
 x64_sys_call+0x2957/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:189
 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: 0x00000000 -> 0x00280040

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 25807 Comm: syz-executor.4 Tainted: G        W          6.10.0-rc4-syzkaller-00052-ge5b3efbe1ab1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/06/20 04:37 upstream e5b3efbe1ab1 41b7e219 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __d_instantiate / lookup_fast
* Struck through repros no longer work on HEAD.