WARNING: lock held when returning to user space in tcp

WARNING: lock held when returning to user space in tcp_setsockopt (2)
Status: fixed on 2022/03/08 16:11
Reported-by: syzbot+@syzkaller.appspotmail.com
Fix commit: b29fcfb54cd7 mptcp: full disconnect implementation
First crash: 160d, last: 154d

Cause bisection: introduced by (bisect log) :
commit 40947e13997a1cba4e875893ca6e5d5e61a0689d
Author: Florian Westphal <fw@strlen.de>
Date: Fri Feb 12 23:59:56 2021 +0000

mptcp: schedule worker when subflow is closed

Crash: WARNING: lock held when returning to user space in tcp_setsockopt (log)
Repro: C syz .config

Fix bisection: fixed by (bisect log) :
commit b29fcfb54cd70caca5b11c80d8d238854938884a
Author: Paolo Abeni <pabeni@redhat.com>
Date: Fri Jan 7 00:20:16 2022 +0000

mptcp: full disconnect implementation

similar bugs (1):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	WARNING: lock held when returning to user space in tcp_setsockopt				1	262d	262d	0/22	auto-closed as invalid on 2021/11/06 22:39

Sample crash report:

================================================
WARNING: lock held when returning to user space!
5.16.0-rc5-syzkaller #0 Not tainted
------------------------------------------------
syz-executor376/4302 is leaving the kernel with locks still held!
1 lock held by syz-executor376/4302:
 #0: ffff8880789a1aa0 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1645 [inline]
 #0: ffff8880789a1aa0 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: do_tcp_setsockopt net/ipv4/tcp.c:3370 [inline]
 #0: ffff8880789a1aa0 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1645 [inline] net/ipv4/tcp.c:3658
 #0: ffff8880789a1aa0 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: do_tcp_setsockopt net/ipv4/tcp.c:3370 [inline] net/ipv4/tcp.c:3658
 #0: ffff8880789a1aa0 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: tcp_setsockopt+0x5b8/0x2520 net/ipv4/tcp.c:3658 net/ipv4/tcp.c:3658

Crashes (6):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci-upstream-net-this-kasan-gce	2021/12/19 07:37	net	60ec7fcfe768	44068e19	.config	log	report	syz	C		WARNING: lock held when returning to user space in tcp_setsockopt
ci-upstream-net-kasan-gce	2021/12/19 09:53	net-next	f85b244ee395	44068e19	.config	log	report	syz	C		WARNING: lock held when returning to user space in tcp_setsockopt
ci-upstream-net-this-kasan-gce	2021/12/23 12:52	net	d1652b70d07c	6caa12e4	.config	log	report			info	WARNING: lock held when returning to user space in tcp_setsockopt
ci-upstream-net-this-kasan-gce	2021/12/19 20:50	net	60ec7fcfe768	44068e19	.config	log	report			info	WARNING: lock held when returning to user space in tcp_setsockopt
ci-upstream-net-this-kasan-gce	2021/12/19 07:09	net	60ec7fcfe768	44068e19	.config	log	report			info	WARNING: lock held when returning to user space in tcp_setsockopt
ci-upstream-net-kasan-gce	2021/12/25 05:36	net-next	7467d716583e	6caa12e4	.config	log	report			info	WARNING: lock held when returning to user space in tcp_setsockopt