KASAN: null-ptr-deref Read in __fget

KASAN: null-ptr-deref Read in __fget_light
Status: upstream: reported on 2021/02/28 09:59
Reported-by: syzbot+21c62f4403f8c167e6f6@syzkaller.appspotmail.com
First crash: 163d, last: 63d

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KMSAN: uninit-value in __fget_light				1	1200d	1200d	0/22	closed as invalid on 2018/06/27 15:08
upstream	KMSAN: uninit-value in __fget_light (2)	C			18	279d	288d	17/22	fixed on 2020/11/16 12:12

Sample crash report:

==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:71 [inline]
BUG: KASAN: null-ptr-deref in atomic_read include/asm-generic/atomic-instrumented.h:27 [inline]
BUG: KASAN: null-ptr-deref in __fget_light+0x4f/0x280 fs/file.c:930
Read of size 4 at addr 0000000000000000 by task io_wqe_worker-0/10248

CPU: 0 PID: 10248 Comm: io_wqe_worker-0 Not tainted 5.11.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0xfa/0x151 lib/dump_stack.c:120
 __kasan_report mm/kasan/report.c:400 [inline]
 kasan_report.cold+0x5f/0xd5 mm/kasan/report.c:413
 check_memory_region_inline mm/kasan/generic.c:179 [inline]
 check_memory_region+0x13d/0x180 mm/kasan/generic.c:185
 instrument_atomic_read include/linux/instrumented.h:71 [inline]
 atomic_read include/asm-generic/atomic-instrumented.h:27 [inline]
 __fget_light+0x4f/0x280 fs/file.c:930
 fdget_raw include/linux/file.h:70 [inline]
 path_init+0xc24/0x1800 fs/namei.c:2275
 path_lookupat+0x30/0x830 fs/namei.c:2331
 filename_lookup+0x19f/0x560 fs/namei.c:2374
 user_path_at include/linux/namei.h:60 [inline]
 vfs_statx+0x142/0x390 fs/stat.c:185
 do_statx+0xd9/0x160 fs/stat.c:580
 io_statx fs/io_uring.c:4525 [inline]
 io_issue_sqe+0x2c87/0x4ec0 fs/io_uring.c:6343
 io_wq_submit_work+0x2a7/0x3f0 fs/io_uring.c:6418
 io_worker_handle_work+0xe2f/0x1d00 fs/io-wq.c:561
 io_wqe_worker+0xc2c/0x1080 fs/io-wq.c:603
 kthread+0x3b1/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
==================================================================

Crashes (4):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Title
ci-upstream-kasan-gce	2021/02/23 18:18	upstream	3b9cdafb5358	fcc6d71b	.config	log	report	info	KASAN: null-ptr-deref Read in __fget_light
ci-upstream-kmsan-gce-386	2021/06/02 22:36	https://github.com/google/kmsan.git master	6099c9da2f7d	0740de69	.config	log	report	info	KMSAN: uninit-value in __fget_light
ci-upstream-kmsan-gce-386	2021/05/28 09:56	https://github.com/google/kmsan.git master	6099c9da2f7d	858ea628	.config	log	report	info	KMSAN: uninit-value in __fget_light
ci-upstream-kmsan-gce-386	2021/05/28 07:58	https://github.com/google/kmsan.git master	6099c9da2f7d	858ea628	.config	log	report	info	KMSAN: uninit-value in __fget_light