syzbot


possible deadlock in inet_stream_connect

Status: auto-obsoleted due to no activity on 2022/09/12 13:57
Reported-by: syzbot+b0f5178b61ed7f3bbb46@syzkaller.appspotmail.com
First crash: 590d, last: 588d

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: possible deadlock in inet_stream_connect (log)
Repro: C syz .config

Fix bisection: fixed by (bisect log) [no-op commit]:
commit 5edf8bd6f4a225f7ad0501f921f9717df152e7fb
Author: Niklas SΓΆderlund <niklas.soderlund+renesas@ragnatech.se>
Date: Wed Dec 9 20:07:37 2020 +0000

  arm64: dts: renesas: rcar-gen3: Add missing CMT nodes

Patch testing requests:
Created Duration User Patch Repo Result
2022/09/12 09:27 18m net-next OK log
2022/09/12 06:27 18m net-next OK log

Sample crash report:
============================================
WARNING: possible recursive locking detected
5.11.0-rc7-syzkaller #0 Not tainted
--------------------------------------------
syz-executor845/10119 is trying to acquire lock:
ffff888021e6e320 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1598 [inline]
ffff888021e6e320 (sk_lock-AF_INET6){+.+.}-{0:0}, at: inet_stream_connect+0x3f/0xa0 net/ipv4/af_inet.c:724

but task is already holding lock:
ffff888022c1a520 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1598 [inline]
ffff888022c1a520 (sk_lock-AF_INET6){+.+.}-{0:0}, at: mptcp_stream_connect+0x85/0x800 net/mptcp/protocol.c:3171

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(sk_lock-AF_INET6);
  lock(sk_lock-AF_INET6);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

1 lock held by syz-executor845/10119:
 #0: ffff888022c1a520 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1598 [inline]
 #0: ffff888022c1a520 (sk_lock-AF_INET6){+.+.}-{0:0}, at: mptcp_stream_connect+0x85/0x800 net/mptcp/protocol.c:3171

stack backtrace:
CPU: 0 PID: 10119 Comm: syz-executor845 Not tainted 5.11.0-rc7-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+0x107/0x163 lib/dump_stack.c:120
 print_deadlock_bug kernel/locking/lockdep.c:2761 [inline]
 check_deadlock kernel/locking/lockdep.c:2804 [inline]
 validate_chain kernel/locking/lockdep.c:3595 [inline]
 __lock_acquire.cold+0x114/0x39e kernel/locking/lockdep.c:4832
 lock_acquire kernel/locking/lockdep.c:5442 [inline]
 lock_acquire+0x1a8/0x720 kernel/locking/lockdep.c:5407
 lock_sock_nested+0xc5/0x110 net/core/sock.c:3071
 lock_sock include/net/sock.h:1598 [inline]
 inet_stream_connect+0x3f/0xa0 net/ipv4/af_inet.c:724
 mptcp_stream_connect+0x156/0x800 net/mptcp/protocol.c:3200
 __sys_connect_file+0x155/0x1a0 net/socket.c:1835
 __sys_connect+0x161/0x190 net/socket.c:1852
 __do_sys_connect net/socket.c:1862 [inline]
 __se_sys_connect net/socket.c:1859 [inline]
 __x64_sys_connect+0x6f/0xb0 net/socket.c:1859
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x443ce9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 a1 15 00 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff5f9324e8 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000443ce9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 000000a800000000 R09: 000000a800000000
R10: 000000a800000000 R11: 0000000000000246 R12: 00007fff5f932500
R13: 00007fff5f932510 R14: 0000000000014e11 R15: 00007fff5f9324f0

Crashes (3):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-net-kasan-gce 2021/02/16 21:33 net-next 9ec5eea5b6ac 98682e5e .config log report syz C possible deadlock in inet_stream_connect
ci-upstream-net-kasan-gce 2021/02/15 05:06 net-next c48f86071027 98682e5e .config log report syz C possible deadlock in inet_stream_connect
ci-upstream-net-kasan-gce 2021/02/16 05:25 net-next d2a04370817f 98682e5e .config log report info possible deadlock in inet_stream_connect
* Struck through repros no longer work on HEAD.