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KCSAN: data-race in d_delete / walk_component

Status: auto-closed as invalid on 2020/04/29 19:58
Subsystems: fs
[Documentation on labels]
First crash: 1559d, last: 1525d

Sample crash report:
==================================================================
BUG: KCSAN: data-race in d_delete / walk_component

write to 0xffff88812532ca80 of 4 bytes by task 8054 on cpu 0:
 d_delete fs/dcache.c:2450 [inline]
 d_delete+0xcc/0xe0 fs/dcache.c:2440
 vfs_unlink+0x398/0x3e0 fs/namei.c:4087
 do_unlinkat+0x32b/0x530 fs/namei.c:4137
 __do_sys_unlink fs/namei.c:4184 [inline]
 __se_sys_unlink fs/namei.c:4182 [inline]
 __x64_sys_unlink+0x3b/0x50 fs/namei.c:4182
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812532ca80 of 4 bytes by task 4028 on cpu 1:
 d_is_symlink include/linux/dcache.h:419 [inline]
 step_into fs/namei.c:1878 [inline]
 walk_component+0xe9/0x9c0 fs/namei.c:1929
 lookup_last fs/namei.c:2391 [inline]
 path_lookupat.isra.0+0x129/0x2e0 fs/namei.c:2436
 filename_lookup+0x145/0x2b0 fs/namei.c:2466
 user_path_at_empty+0x4c/0x70 fs/namei.c:2746
 do_readlinkat+0x84/0x220 fs/stat.c:409
 __do_sys_readlink fs/stat.c:442 [inline]
 __se_sys_readlink fs/stat.c:439 [inline]
 __x64_sys_readlink+0x51/0x70 fs/stat.c:439
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4028 Comm: udevd Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/02/19 19:57 https://github.com/google/ktsan.git kcsan b12d66a6c34f 47fae6e9 .config console log report ci2-upstream-kcsan-gce
2020/01/17 09:06 https://github.com/google/ktsan.git kcsan 245a43005292 3de7aabb .config console log report ci2-upstream-kcsan-gce
* Struck through repros no longer work on HEAD.