Re: [syzbot] WARNING: bad unlock balance in rxrpc_do_sendmsg

From: Khalid Masum <khalid.masum.92@gmail.com>
To: syzbot+7f0483225d0c94cb3441@syzkaller.appspotmail.com
Cc: David Howells <dhowells@redhat.com>,
	Marc Dionne <marc.dionne@auristor.com>,
	"David S . Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org,
	netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com,
	linux-kernel-mentees@lists.linuxfoundation.org,
	paskripkin@gmail.com, skhan@linuxfoundation.org,
	18801353760@163.com, Hawkins Jiawei <yin31149@gmail.com>,
	Khalid Masum <khalid.masum.92@gmail.com>
Subject: Re: [syzbot] WARNING: bad unlock balance in rxrpc_do_sendmsg
Date: Mon, 22 Aug 2022 01:17:51 +0600	[thread overview]
Message-ID: <20220821191751.222357-1-khalid.masum.92@gmail.com> (raw)
In-Reply-To: <000000000000ce327f05d537ebf7@google.com>

Maybe we do not need to lock since no other timer_schedule needs 
it. 

Test if this fixes the issue.
---
#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 568035b01cfb
 net/rxrpc/sendmsg.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index 1d38e279e2ef..640e2ab2cc35 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -51,10 +51,8 @@ static int rxrpc_wait_for_tx_window_intr(struct rxrpc_sock *rx,
 			return sock_intr_errno(*timeo);
 
 		trace_rxrpc_transmit(call, rxrpc_transmit_wait);
-		mutex_unlock(&call->user_mutex);
 		*timeo = schedule_timeout(*timeo);
-		if (mutex_lock_interruptible(&call->user_mutex) < 0)
-			return sock_intr_errno(*timeo);
+		return sock_intr_errno(*timeo);
 	}
 }
 
-- 
2.37.1

