KCSAN: data-race in dput / vfs

KCSAN: data-race in dput / vfs_rmdir
Status: auto-closed as invalid on 2020/09/30 12:38
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 416d, last: 416d

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in dput / vfs_rmdir (2)				2	339d	313d	0/22	auto-closed as invalid on 2020/12/21 11:51
upstream	KCSAN: data-race in dput / vfs_rmdir (3)				3	241d	278d	0/22	auto-closed as invalid on 2021/03/25 09:59

Sample crash report:

==================================================================
BUG: KCSAN: data-race in dput / vfs_rmdir

write to 0xffff88811e9c8240 of 4 bytes by task 20876 on cpu 1:
 dont_mount include/linux/dcache.h:354 [inline]
 vfs_rmdir+0x1a6/0x2a0 fs/namei.c:3718
 do_rmdir+0x16e/0x300 fs/namei.c:3773
 __do_sys_rmdir fs/namei.c:3791 [inline]
 __se_sys_rmdir fs/namei.c:3789 [inline]
 __x64_sys_rmdir+0x2c/0x30 fs/namei.c:3789
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88811e9c8240 of 4 bytes by task 20881 on cpu 0:
 fast_dput fs/dcache.c:746 [inline]
 dput+0x2f/0x420 fs/dcache.c:865
 path_put fs/namei.c:496 [inline]
 do_unlinkat+0x37a/0x4d0 fs/namei.c:3911
 __do_sys_unlink fs/namei.c:3942 [inline]
 __se_sys_unlink fs/namei.c:3940 [inline]
 __x64_sys_unlink+0x2c/0x30 fs/namei.c:3940
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 20881 Comm: systemd-udevd Not tainted 5.9.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 20881 Comm: systemd-udevd Not tainted 5.9.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x10f/0x19d lib/dump_stack.c:118
 panic+0x207/0x64a kernel/panic.c:231
 kcsan_report+0x684/0x690 kernel/kcsan/report.c:630
 kcsan_setup_watchpoint+0x41e/0x4a0 kernel/kcsan/core.c:540
 fast_dput fs/dcache.c:746 [inline]
 dput+0x2f/0x420 fs/dcache.c:865
 path_put fs/namei.c:496 [inline]
 do_unlinkat+0x37a/0x4d0 fs/namei.c:3911
 __do_sys_unlink fs/namei.c:3942 [inline]
 __se_sys_unlink fs/namei.c:3940 [inline]
 __x64_sys_unlink+0x2c/0x30 fs/namei.c:3940
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fe3d4de90e7
Code: f0 ff ff 73 01 c3 48 8b 0d ae bd 2b 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 81 bd 2b 00 f7 d8 64 89 01 48
RSP: 002b:00007ffcedd19668 EFLAGS: 00000246 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 00007ffcedd19aa0 RCX: 00007fe3d4de90e7
RDX: 0000000000000000 RSI: 00000000000007ab RDI: 00007ffcedd1a2a0
RBP: 00007ffcedd1a2a0 R08: 000000000000c000 R09: 0000000000000000
R10: 00005572d5debe80 R11: 0000000000000246 R12: 00007ffcedd1abb0
R13: 00005572d5debe10 R14: 00005572d5de5030 R15: 000000000000000e
Kernel Offset: disabled
Rebooting in 86400 seconds..

Crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-upstream-kcsan-gce	2020/08/26 12:33	upstream	2ac69819ba9e	318430cb	.config	log	report