Re: [Bluez-devel] rfcomm_sock_sendmsg with len==0 (in Linux 2.6.18)

[Marcel Holtmann <marcel@holtmann.org>]

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Hi Tuomas,

> > > rfcomm_sock_sendmsg() in net/bluetooth/rfcomm/sock.c. It returns
> > > uninitialized variable err, if called with len==0.
> > >
> > > Simple fix is to initialize err to 0.
> >
> > this would only hide the real problem. It should only return err if
> > the sent is still 0. The return statement is
> >
> > 	return sent ? sent : err;
> 
> Yep, exactly. It returns err, which isn't initialized, so it could be 
> positive.
> 
> Am I missing something?

that is really strange. A recent compiler should detect that err can be
used uninitialized.

How about the attached patch. Does it work for you?

Regards

Marcel


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diff --git a/net/bluetooth/rfcomm/sock.c b/net/bluetooth/rfcomm/sock.c
index 544d65b..4297ff6 100644
--- a/net/bluetooth/rfcomm/sock.c
+++ b/net/bluetooth/rfcomm/sock.c
@@ -557,7 +557,6 @@ static int rfcomm_sock_sendmsg(struct kiocb *iocb, struct socket *sock,
 	struct sock *sk = sock->sk;
 	struct rfcomm_dlc *d = rfcomm_pi(sk)->dlc;
 	struct sk_buff *skb;
-	int err;
 	int sent = 0;
 
 	if (msg->msg_flags & MSG_OOB)
@@ -572,6 +571,7 @@ static int rfcomm_sock_sendmsg(struct kiocb *iocb, struct socket *sock,
 
 	while (len) {
 		size_t size = min_t(size_t, len, d->mtu);
+		int err;
 		
 		skb = sock_alloc_send_skb(sk, size + RFCOMM_SKB_RESERVE,
 				msg->msg_flags & MSG_DONTWAIT, &err);
@@ -589,6 +589,7 @@ static int rfcomm_sock_sendmsg(struct kiocb *iocb, struct socket *sock,
 		err = rfcomm_dlc_send(d, skb);
 		if (err < 0) {
 			kfree_skb(skb);
+			sent = err;
 			break;
 		}
 
@@ -598,7 +599,7 @@ static int rfcomm_sock_sendmsg(struct kiocb *iocb, struct socket *sock,
 
 	release_sock(sk);
 
-	return sent ? sent : err;
+	return sent;
 }
 
 static long rfcomm_sock_data_wait(struct sock *sk, long timeo)

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