WARNING: refcount bug in free

WARNING: refcount bug in free_nsproxy (2)
Status: upstream: reported C repro on 2020/01/14 22:04
Reported-by: syzbot+a98eee31f5df4261d88c@syzkaller.appspotmail.com
First crash: 525d, last: 405d

Cause bisection: introduced by (bisect log) :
commit 14215108a1fd7e002c0a1f9faf8fbaf41fdda50d
Author: Cong Wang <xiyou.wangcong@gmail.com>
Date: Thu Feb 21 05:37:42 2019 +0000

net_sched: initialize net pointer inside tcf_exts_init()

Crash: KASAN: use-after-free Read in cleanup_net (log)
Repro: C syz .config

Fix bisection: failed (bisect log)

similar bugs (1):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	WARNING: refcount bug in free_nsproxy				4	1177d	1202d	6/22	fixed on 2018/05/08 18:30

Patch testing requests:
Created	Duration	User	Patch	Repo	Result
2020/09/11 09:33	9m	anant.thazhemadam@gmail.com		https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master	report log

Sample crash report:

IPVS: ftp: loaded support on port[0] = 21
netlink: 16 bytes leftover after parsing attributes in process `syz-executor107'.
------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 1 PID: 6979 at lib/refcount.c:28 refcount_warn_saturate+0x15b/0x1a0 lib/refcount.c:28
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 6979 Comm: syz-executor107 Not tainted 5.6.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1e9/0x30e lib/dump_stack.c:118
 panic+0x264/0x7a0 kernel/panic.c:221
 __warn+0x209/0x210 kernel/panic.c:582
 report_bug+0x1ac/0x2d0 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:175 [inline]
 do_error_trap+0xca/0x1c0 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:refcount_warn_saturate+0x15b/0x1a0 lib/refcount.c:28
Code: c7 6a 77 f2 88 31 c0 e8 f3 b7 ad fd 0f 0b eb 85 e8 2a a4 db fd c6 05 ef 45 cd 05 01 48 c7 c7 96 77 f2 88 31 c0 e8 d5 b7 ad fd <0f> 0b e9 64 ff ff ff e8 09 a4 db fd c6 05 cf 45 cd 05 01 48 c7 c7
RSP: 0018:ffffc90000f97d98 EFLAGS: 00010246
RAX: e55b4ee8dc4a2100 RBX: 0000000000000003 RCX: ffff8880a8606540
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 0000000000000003 R08: ffffffff815f5a86 R09: ffffed1015d26668
R10: ffffed1015d26668 R11: 0000000000000000 R12: ffff8880a804a040
R13: 0000000000000100 R14: ffff8880a9a8cc30 R15: ffff8880a804a044
 refcount_sub_and_test include/linux/refcount.h:261 [inline]
 refcount_dec_and_test include/linux/refcount.h:281 [inline]
 put_net include/net/net_namespace.h:264 [inline]
 free_nsproxy+0x343/0x3b0 kernel/nsproxy.c:206
 do_exit+0x5ea/0x1f80 kernel/exit.c:794
 do_group_exit+0x15e/0x2c0 kernel/exit.c:893
 __do_sys_exit_group+0x13/0x20 kernel/exit.c:904
 __se_sys_exit_group+0x10/0x10 kernel/exit.c:902
 __x64_sys_exit_group+0x37/0x40 kernel/exit.c:902
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x43f998
Code: Bad RIP value.
RSP: 002b:00007fff7f3413d8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 000000000043f998
RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001
RBP: 00000000004bfa10 R08: 00000000000000e7 R09: ffffffffffffffd0
R10: 0000000120080522 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000006d11c0 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..

Crashes (103):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro
ci-upstream-kasan-gce-smack-root	2020/04/07 04:51	upstream	7e634208	99a96044	.config	log	report	syz	C
ci-upstream-kasan-gce-selinux-root	2020/04/03 22:53	upstream	bef7b2a7	5ed396e6	.config	log	report	syz	C
ci-upstream-kasan-gce-selinux-root	2020/04/02 13:50	upstream	919dce24	a34e2c33	.config	log	report	syz	C
ci-upstream-kasan-gce-root	2020/04/01 20:11	upstream	1a323ea5	a34e2c33	.config	log	report	syz	C
ci-upstream-kasan-gce-root	2020/03/31 07:22	upstream	673b41e0	c8d1cc20	.config	log	report	syz	C
ci-upstream-kasan-gce-smack-root	2020/03/30 21:40	upstream	7111951b	c8d1cc20	.config	log	report	syz	C
ci-upstream-kasan-gce-selinux-root	2020/03/30 16:55	upstream	7111951b	c8d1cc20	.config	log	report	syz	C
ci-upstream-kasan-gce-smack-root	2020/03/30 16:48	upstream	7111951b	c8d1cc20	.config	log	report	syz	C
ci-upstream-kasan-gce-selinux-root	2020/03/30 05:31	upstream	e595dd94	05736b29	.config	log	report	syz	C
ci-upstream-kasan-gce-root	2020/03/29 07:29	upstream	906c4043	05736b29	.config	log	report	syz	C
ci-upstream-kasan-gce-root	2020/03/28 23:37	upstream	69c5eea3	f1ebdfba	.config	log	report	syz	C
ci-upstream-kasan-gce-smack-root	2020/03/28 23:14	upstream	69c5eea3	f1ebdfba	.config	log	report	syz	C
ci-upstream-kasan-gce-selinux-root	2020/03/28 14:20	upstream	69c5eea3	f1ebdfba	.config	log	report	syz	C
ci-upstream-kasan-gce-root	2020/03/27 02:25	upstream	9420e8ad	6d25c5a0	.config	log	report	syz	C
ci-upstream-kasan-gce-selinux-root	2020/03/21 20:44	upstream	5ad0ec0b	4288d95e	.config	log	report	syz	C
ci-upstream-kasan-gce-selinux-root	2020/03/21 19:49	upstream	5ad0ec0b	4288d95e	.config	log	report	syz	C
ci-upstream-kasan-gce-selinux-root	2020/03/21 18:33	upstream	5ad0ec0b	4288d95e	.config	log	report	syz	C
ci-upstream-kasan-gce	2020/03/18 05:04	upstream	ac309e77	97bc55ce	.config	log	report	syz	C
ci-upstream-kasan-gce-root	2020/03/18 04:31	upstream	ac309e77	97bc55ce	.config	log	report	syz	C
ci-upstream-kasan-gce-root	2020/03/18 03:42	upstream	ac309e77	97bc55ce	.config	log	report	syz	C
ci-upstream-kasan-gce-smack-root	2020/03/17 05:33	upstream	fb33c651	749688d2	.config	log	report	syz	C
ci-upstream-kasan-gce-smack-root	2020/03/17 04:52	upstream	fb33c651	749688d2	.config	log	report	syz	C
ci-upstream-kasan-gce-smack-root	2020/03/17 03:52	upstream	fb33c651	749688d2	.config	log	report	syz	C
ci-upstream-kasan-gce	2020/03/16 20:49	upstream	fb33c651	749688d2	.config	log	report	syz	C
ci-upstream-kasan-gce	2020/03/15 06:00	upstream	69a4d0ba	749688d2	.config	log	report	syz	C
ci-upstream-kasan-gce	2020/03/14 23:06	upstream	69a4d0ba	749688d2	.config	log	report	syz	C
ci-upstream-kasan-gce	2020/03/13 16:18	upstream	3cc6e2c5	d850e9d0	.config	log	report	syz	C
ci-upstream-kasan-gce-selinux-root	2020/03/12 03:39	upstream	e3a36eb6	e7caca8e	.config	log	report	syz	C
ci-upstream-kasan-gce-386	2020/03/18 05:14	upstream	ac309e77	97bc55ce	.config	log	report	syz	C
ci-upstream-kasan-gce-386	2020/03/17 04:34	upstream	fb33c651	749688d2	.config	log	report	syz	C
ci-upstream-kasan-gce-386	2020/03/15 21:35	upstream	d3dca690	749688d2	.config	log	report	syz	C
ci-upstream-kasan-gce-386	2020/03/15 17:29	upstream	d3dca690	749688d2	.config	log	report	syz	C
ci-upstream-kasan-gce-386	2020/03/13 15:56	upstream	3cc6e2c5	d850e9d0	.config	log	report	syz	C
ci-upstream-net-this-kasan-gce	2020/03/17 17:07	net	32ca98fe	749688d2	.config	log	report	syz	C
ci-upstream-net-this-kasan-gce	2020/03/16 20:16	net	ef299cc3	749688d2	.config	log	report	syz	C
ci-upstream-net-this-kasan-gce	2020/03/16 00:32	net	0fda7600	749688d2	.config	log	report	syz	C
ci-upstream-net-this-kasan-gce	2020/03/14 00:26	net	b09fe70e	d850e9d0	.config	log	report	syz	C
ci-upstream-net-this-kasan-gce	2020/03/10 18:26	net	23620594	35f53e45	.config	log	report	syz	C
ci-upstream-net-kasan-gce	2020/03/16 02:14	net-next	5d0ab06b	749688d2	.config	log	report	syz	C
ci-upstream-net-kasan-gce	2020/03/15 02:51	net-next	94229d45	749688d2	.config	log	report	syz	C
ci-upstream-net-kasan-gce	2020/03/14 14:44	net-next	1d343579	749688d2	.config	log	report	syz	C
ci-upstream-net-kasan-gce	2020/03/13 12:01	net-next	93e61613	d850e9d0	.config	log	report	syz	C
ci-upstream-linux-next-kasan-gce-root	2020/04/10 23:03	linux-next	0434e521	a8c6a3f8	.config	log	report	syz	C
ci-upstream-linux-next-kasan-gce-root	2020/04/08 17:50	linux-next	5798bd75	db9bcd4b	.config	log	report	syz	C
ci-upstream-linux-next-kasan-gce-root	2020/04/08 13:36	linux-next	5798bd75	db9bcd4b	.config	log	report	syz	C
ci-upstream-linux-next-kasan-gce-root	2020/04/07 04:03	linux-next	b2e2a818	99a96044	.config	log	report	syz	C
ci-upstream-linux-next-kasan-gce-root	2020/03/29 01:28	linux-next	770fbb32	05736b29	.config	log	report	syz	C
ci-upstream-linux-next-kasan-gce-root	2020/03/28 23:18	linux-next	770fbb32	f1ebdfba	.config	log	report	syz	C
ci-upstream-linux-next-kasan-gce-root	2020/03/22 08:48	linux-next	770fbb32	78267cec	.config	log	report	syz	C
ci-upstream-linux-next-kasan-gce-root	2020/03/13 18:37	linux-next	770fbb32	d850e9d0	.config	log	report	syz	C
ci-upstream-linux-next-kasan-gce-root	2020/01/11 18:53	linux-next	6c09d7db	4c04afaa	.config	log	report	syz	C