KCSAN: data-race in vfs_readlink / vfs

KCSAN: data-race in vfs_readlink / vfs_unlink
Status: closed as invalid on 2020/06/18 14:24
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 450d, last: 288d

similar bugs (1):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in vfs_readlink / vfs_unlink (2)				137	7d08h	156d	0/21	moderation: reported on 2020/09/28 07:47

Sample crash report:

==================================================================
BUG: KCSAN: data-race in vfs_readlink / vfs_unlink

write to 0xffff8880baf14e40 of 4 bytes by task 9014 on cpu 1:
 dont_mount include/linux/dcache.h:352 [inline]
 vfs_unlink+0x267/0x400 fs/namei.c:3811
 do_unlinkat+0x33f/0x550 fs/namei.c:3873
 __do_sys_unlink fs/namei.c:3920 [inline]
 __se_sys_unlink fs/namei.c:3918 [inline]
 __x64_sys_unlink+0x38/0x50 fs/namei.c:3918
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880baf14e40 of 4 bytes by task 5282 on cpu 0:
 d_is_symlink include/linux/dcache.h:419 [inline]
 vfs_readlink+0x1b3/0x250 fs/namei.c:4536
 do_readlinkat+0x200/0x230 fs/stat.c:421
 __do_sys_readlink fs/stat.c:442 [inline]
 __se_sys_readlink fs/stat.c:439 [inline]
 __x64_sys_readlink+0x4c/0x60 fs/stat.c:439
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 5282 Comm: systemd-udevd Not tainted 5.7.0-rc1-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: 5282 Comm: systemd-udevd Not tainted 5.7.0-rc1-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+0x11d/0x187 lib/dump_stack.c:118
 panic+0x210/0x640 kernel/panic.c:221
 kcsan_report.cold+0xc/0x1a kernel/kcsan/report.c:626
 kcsan_setup_watchpoint+0x3fb/0x440 kernel/kcsan/core.c:519
 d_is_symlink include/linux/dcache.h:419 [inline]
 vfs_readlink+0x1b3/0x250 fs/namei.c:4536
 do_readlinkat+0x200/0x230 fs/stat.c:421
 __do_sys_readlink fs/stat.c:442 [inline]
 __se_sys_readlink fs/stat.c:439 [inline]
 __x64_sys_readlink+0x4c/0x60 fs/stat.c:439
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f8417964087
Code: 73 01 c3 48 8b 0d 11 be 2b 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 59 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e1 bd 2b 00 f7 d8 64 89 01 48
RSP: 002b:00007ffc5c768b58 EFLAGS: 00000293 ORIG_RAX: 0000000000000059
RAX: ffffffffffffffda RBX: 00007ffc5c768bf0 RCX: 00007f8417964087
RDX: 0000000000000200 RSI: 00007ffc5c768d00 RDI: 00007ffc5c768bd0
RBP: 00007ffc5c769158 R08: 0000000000000001 R09: 0000000000000014
R10: 0000000000000064 R11: 0000000000000293 R12: 00007ffc5c768d00
R13: 000056062956f010 R14: 000056062956f0e0 R15: 00007ffc5c768bd0
Kernel Offset: disabled
Rebooting in 86400 seconds..

Crashes (12):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report
ci2-upstream-kcsan-gce	2020/05/19 12:07	https://github.com/google/ktsan.git kcsan	7c3cd68e	6d882fd2	.config	log	report
ci2-upstream-kcsan-gce	2020/05/15 04:17	https://github.com/google/ktsan.git kcsan	7c3cd68e	2d572622	.config	log	report
ci2-upstream-kcsan-gce	2020/05/13 04:48	https://github.com/google/ktsan.git kcsan	7c3cd68e	a44eb8f7	.config	log	report
ci2-upstream-kcsan-gce	2020/04/18 17:34	https://github.com/google/ktsan.git kcsan	7c3cd68e	365fba24	.config	log	report
ci2-upstream-kcsan-gce	2020/03/31 08:21	https://github.com/google/ktsan.git kcsan	40959e34	c8d1cc20	.config	log	report
ci2-upstream-kcsan-gce	2020/03/19 11:36	https://github.com/google/ktsan.git kcsan	40959e34	2c31c529	.config	log	report
ci2-upstream-kcsan-gce	2020/02/03 00:12	https://github.com/google/ktsan.git kcsan	245a4300	93e5e335	.config	log	report
ci2-upstream-kcsan-gce	2020/01/30 12:48	https://github.com/google/ktsan.git kcsan	245a4300	5ed23f9a	.config	log	report
ci2-upstream-kcsan-gce	2020/01/22 03:45	https://github.com/google/ktsan.git kcsan	245a4300	8eda0b95	.config	log	report
ci2-upstream-kcsan-gce	2020/01/16 11:00	https://github.com/google/ktsan.git kcsan	245a4300	f9b69507	.config	log	report
ci2-upstream-kcsan-gce	2019/12/29 14:37	https://github.com/google/ktsan.git kcsan	245a4300	af6b8ef8	.config	log	report
ci2-upstream-kcsan-gce	2019/12/09 06:44	https://github.com/google/ktsan.git kcsan	ef798c30	1508f453	.config	log	report