WARNING in inc

WARNING in inc_nlink
Status: fixed on 2020/09/11 09:49
Reported-by: syzbot+e119c3cedf831cd93c5b@syzkaller.appspotmail.com
Fix commit: 12490f06ef08 fs/minix: don't allow getting deleted inodes
First crash: 787d, last: 644d

Fix bisection: fixed by (bisect log) :
commit 12490f06ef084bc34f5e5dbda104aa034e376f2e
Author: Eric Biggers <ebiggers@google.com>
Date: Wed Aug 12 01:35:27 2020 +0000

fs/minix: don't allow getting deleted inodes

similar bugs (6):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
linux-4.19	WARNING in inc_nlink (2)	C		error	83	7h20m	562d	0/1	upstream: reported C repro on 2020/11/01 15:25
upstream	WARNING in inc_nlink (2)	C	inconclusive	done	21	71d	408d	22/22	fixed on 2022/03/08 16:11
upstream	WARNING in inc_nlink (3)	C	error		89	6h51m	61d	0/22	upstream: reported C repro on 2022/03/17 16:37
linux-4.19	WARNING in inc_nlink	C		done	8	637d	786d	1/1	fixed on 2020/09/18 07:23
linux-4.14	WARNING in inc_nlink (2)	C			47	26d	558d	0/1	upstream: reported C repro on 2020/11/06 09:55
upstream	WARNING in inc_nlink	C	done		26	674d	777d	17/22	fixed on 2020/09/16 22:51

Sample crash report:

audit: type=1400 audit(1590021294.558:8): avc:  denied  { execmem } for  pid=6360 comm="syz-executor076" scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=process permissive=1
MINIX-fs: mounting unchecked file system, running fsck is recommended
------------[ cut here ]------------
WARNING: CPU: 0 PID: 6360 at fs/inode.c:342 inc_nlink+0x113/0x130 fs/inode.c:342
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 6360 Comm: syz-executor076 Not tainted 4.14.181-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x283 lib/dump_stack.c:58
 panic+0x1f9/0x42d kernel/panic.c:183
 __warn.cold+0x2f/0x30 kernel/panic.c:547
 report_bug+0x20a/0x248 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:177 [inline]
 fixup_bug arch/x86/kernel/traps.c:172 [inline]
 do_error_trap+0x195/0x2d0 arch/x86/kernel/traps.c:295
 invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:964
RIP: 0010:inc_nlink+0x113/0x130 fs/inode.c:342
RSP: 0018:ffff88809a2dfdb0 EFLAGS: 00010297
RAX: ffff88809a136240 RBX: ffff888083682970 RCX: 1ffff11013426d57
RDX: 0000000000000000 RSI: ffff88808369bb40 RDI: ffff888083682a48
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000002
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880836829b8
R13: ffff88808369bb40 R14: ffff88808369bb98 R15: 0000000000000000
 inode_inc_link_count include/linux/fs.h:2035 [inline]
 minix_mkdir+0x5a/0x160 fs/minix/namei.c:121
 vfs_mkdir+0x3af/0x620 fs/namei.c:3849
 SYSC_mkdirat fs/namei.c:3872 [inline]
 SyS_mkdirat+0x1b5/0x220 fs/namei.c:3856
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x444a69
RSP: 002b:00007ffd3e0b8558 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00007ffd3e0b8560 RCX: 0000000000444a69
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000240
RBP: 0000000000000000 R08: 0000000000400e50 R09: 0000000000400e50
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004026d0
R13: 0000000000402760 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..

Crashes (21):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro
ci2-linux-4-14	2020/05/21 00:39	linux-4.14.y	a41ba30d9df2	4afdfa20	.config	log	report	syz	C
ci2-linux-4-14	2020/04/15 22:53	linux-4.14.y	c10b57a567e4	3f3c5574	.config	log	report	syz	C
ci2-linux-4-14	2020/04/09 21:08	linux-4.14.y	4520f06b03ae	a8c6a3f8	.config	log	report	syz	C
ci2-linux-4-14	2020/04/03 17:58	linux-4.14.y	4520f06b03ae	5ed396e6	.config	log	report	syz	C
ci2-linux-4-14	2020/03/22 09:30	linux-4.14.y	01364dad1d45	78267cec	.config	log	report	syz	C
ci2-linux-4-14	2020/07/12 14:35	linux-4.14.y	b850307b279c	115e1930	.config	log	report
ci2-linux-4-14	2020/07/12 04:08	linux-4.14.y	b850307b279c	7ba05d2d	.config	log	report
ci2-linux-4-14	2020/07/11 16:32	linux-4.14.y	b850307b279c	7ba05d2d	.config	log	report
ci2-linux-4-14	2020/07/07 11:07	linux-4.14.y	b850307b279c	42723355	.config	log	report
ci2-linux-4-14	2020/06/20 16:46	linux-4.14.y	b850307b279c	c655ec77	.config	log	report
ci2-linux-4-14	2020/05/29 19:34	linux-4.14.y	4f68020fef1c	bed08304	.config	log	report
ci2-linux-4-14	2020/05/21 02:20	linux-4.14.y	a41ba30d9df2	4afdfa20	.config	log	report
ci2-linux-4-14	2020/05/15 03:29	linux-4.14.y	ab9dfda23248	2d572622	.config	log	report
ci2-linux-4-14	2020/05/13 06:06	linux-4.14.y	ab9dfda23248	a44eb8f7	.config	log	report
ci2-linux-4-14	2020/05/04 15:50	linux-4.14.y	773e2b1cd56a	58ae5e18	.config	log	report
ci2-linux-4-14	2020/04/29 06:48	linux-4.14.y	050272a0423e	e3ecea2e	.config	log	report
ci2-linux-4-14	2020/04/04 08:36	linux-4.14.y	4520f06b03ae	ef26b610	.config	log	report
ci2-linux-4-14	2020/04/03 21:27	linux-4.14.y	4520f06b03ae	5ed396e6	.config	log	report
ci2-linux-4-14	2020/03/29 22:18	linux-4.14.y	01364dad1d45	05736b29	.config	log	report
ci2-linux-4-14	2020/03/24 10:44	linux-4.14.y	01364dad1d45	33e14df3	.config	log	report
ci2-linux-4-14	2020/03/22 09:06	linux-4.14.y	01364dad1d45	78267cec	.config	log	report