From: Alex Gartrell <agartrell@fb.com>
Date: Fri, 26 Dec 2014 07:22:49 +0000 (-0800)
Subject: tun: return proper error code from tun_do_read
X-Git-Tag: v3.19.6~23
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6e24551ff94701e62c13c982eca0bc3a682817ad;p=thirdparty%2Fkernel%2Fstable.git

tun: return proper error code from tun_do_read

[ Upstream commit 957f094f221f81e457133b1f4c4d95ffa49ff731 ]

Instead of -1 with EAGAIN, read on a O_NONBLOCK tun fd will return 0.  This
fixes this by properly returning the error code from __skb_recv_datagram.

Signed-off-by: Alex Gartrell <agartrell@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 10f9e4021b5ab..9a409a8f3b19f 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1368,7 +1368,7 @@ static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile,
 	skb = __skb_recv_datagram(tfile->socket.sk, noblock ? MSG_DONTWAIT : 0,
 				  &peeked, &off, &err);
 	if (!skb)
-		return 0;
+		return err;
 
 	ret = tun_put_user(tun, tfile, skb, to);
 	if (unlikely(ret < 0))