WARNING in inc

WARNING in inc_nlink
Status: upstream: reported C repro on 2020/03/31 17:21
Reported-by: syzbot+a9ac3de1b5de5fb10efc@syzkaller.appspotmail.com
Fix commit: fs/minix: don't allow getting deleted inodes
Patched on: [ci-upstream-linux-next-kasan-gce-root], missing on: [ci-qemu-upstream ci-qemu-upstream-386 ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-leak ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce ci-upstream-kmsan-gce-386 ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci2-upstream-kcsan-gce ci2-upstream-usb]
First crash: 131d, last: 26d

Cause bisection: the bug happens on the oldest tested release
Crash: WARNING in sysfs_warn_dup (log)
Repro: C syz .config

similar bugs (2):
Kernel	Title	Repro	Bisected	Count	Last	Reported	Patched	Status
linux-4.19	WARNING in inc_nlink	C		8	19d	137d	0/1	upstream: reported C repro on 2020/03/23 07:48
linux-4.14	WARNING in inc_nlink	C		21	26d	138d	0/1	upstream: reported C repro on 2020/03/22 09:07

Sample crash report:

MINIX-fs: mounting unchecked file system, running fsck is recommended
------------[ cut here ]------------
WARNING: CPU: 0 PID: 7197 at fs/inode.c:360 inc_nlink+0x144/0x160 fs/inode.c:360
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 7197 Comm: syz-executor186 Not tainted 5.7.0-rc6-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+0x188/0x20d lib/dump_stack.c:118
 panic+0x2e3/0x75c kernel/panic.c:221
 __warn.cold+0x2f/0x35 kernel/panic.c:582
 report_bug+0x27b/0x2f0 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:175 [inline]
 fixup_bug arch/x86/kernel/traps.c:170 [inline]
 do_error_trap+0x12b/0x220 arch/x86/kernel/traps.c:267
 do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:inc_nlink+0x144/0x160 fs/inode.c:360
Code: ff 4c 89 e7 e8 ed 70 ee ff e9 42 ff ff ff 4c 89 e7 e8 70 70 ee ff e9 fc fe ff ff 4c 89 e7 e8 63 70 ee ff eb d4 e8 bc 8f b0 ff <0f> 0b e9 6e ff ff ff e8 60 70 ee ff e9 44 ff ff ff e8 56 70 ee ff
RSP: 0018:ffffc90001657d88 EFLAGS: 00010293
RAX: ffff8880962aa600 RBX: ffff888087318a00 RCX: ffffffff81c2a4d0
RDX: 0000000000000000 RSI: ffffffff81c2a564 RDI: 0000000000000007
RBP: 0000000000000000 R08: ffff8880962aa600 R09: ffffed1015440757
R10: ffff8880aa203ab3 R11: ffffed1015440756 R12: ffff888087318a48
R13: ffff8880896a8450 R14: ffff8880896a84b0 R15: 0000000000000000
 inode_inc_link_count include/linux/fs.h:2204 [inline]
 minix_mkdir+0x71/0x1b0 fs/minix/namei.c:117
 vfs_mkdir+0x419/0x690 fs/namei.c:3625
 do_mkdirat+0x21e/0x280 fs/namei.c:3648
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x444a59
Code: 0d d8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db d7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fff6ab18768 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00007fff6ab18770 RCX: 0000000000444a59
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000240
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000400e40
R10: 00007fff6ab18640 R11: 0000000000000246 R12: 00000000004026c0
R13: 0000000000402750 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..

Crashes (26):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	Maintainers
ci-upstream-kasan-gce-root	2020/05/24 22:04	upstream	caffb99b	bd28eb9d	.config	log	report	syz	C	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-selinux-root	2020/05/24 20:31	upstream	caffb99b	bd28eb9d	.config	log	report	syz	C	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-smack-root	2020/05/23 23:05	upstream	423b8baf	9682898d	.config	log	report	syz	C	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-selinux-root	2020/04/25 01:19	upstream	b4f63322	03d97a1b	.config	log	report	syz	C	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-smack-root	2020/04/25 00:52	upstream	b4f63322	03d97a1b	.config	log	report	syz	C	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-selinux-root	2020/04/18 03:03	upstream	95988fbc	435c6d53	.config	log	report	syz	C	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-smack-root	2020/04/18 02:36	upstream	95988fbc	435c6d53	.config	log	report	syz	C	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-smack-root	2020/04/16 17:31	upstream	00086336	c743fcb3	.config	log	report	syz	C	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-selinux-root	2020/04/16 16:29	upstream	00086336	c743fcb3	.config	log	report	syz	C	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-root	2020/04/16 15:00	upstream	00086336	c743fcb3	.config	log	report	syz	C	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-root	2020/04/15 06:14	upstream	8632e9b5	3f3c5574	.config	log	report	syz	C	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-selinux-root	2020/04/13 17:59	upstream	8f3d9f35	17a986e5	.config	log	report	syz	C	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-root	2020/04/11 22:19	upstream	5b8b9d0c	a8c6a3f8	.config	log	report	syz	C	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-root	2020/03/30 05:39	upstream	e595dd94	05736b29	.config	log	report	syz	C	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-linux-next-kasan-gce-root	2020/05/21 08:37	linux-next	ac935d22	c61086ab	.config	log	report	syz	C	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-linux-next-kasan-gce-root	2020/04/25 23:48	linux-next	ac935d22	b8bb8e5f	.config	log	report	syz	C	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-linux-next-kasan-gce-root	2020/04/20 01:30	linux-next	ac935d22	9f7c6d12	.config	log	report	syz	C	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-linux-next-kasan-gce-root	2020/04/19 00:32	linux-next	ac935d22	365fba24	.config	log	report	syz	C	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-linux-next-kasan-gce-root	2020/04/16 13:07	linux-next	ac935d22	c743fcb3	.config	log	report	syz	C	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-root	2020/07/12 20:34	upstream	0aea6d5c	115e1930	.config	log	report			linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-smack-root	2020/07/11 20:21	upstream	a581387e	18d18b59	.config	log	report			linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-selinux-root	2020/07/07 13:13	upstream	7cc2a8ea	51095195	.config	log	report			linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-smack-root	2020/07/07 06:21	upstream	7cc2a8ea	51095195	.config	log	report			linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-selinux-root	2020/04/07 04:30	upstream	7e634208	99a96044	.config	log	report			linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-root	2020/03/30 05:20	upstream	e595dd94	05736b29	.config	log	report			linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-linux-next-kasan-gce-root	2020/04/03 06:47	linux-next	770fbb32	a34e2c33	.config	log	report			linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk