[stable,<=,3.18] net: add length argument to skb_copy_and_csum_datagram_iovec
diff mbox

Message ID 1447349202.22599.30.camel@edumazet-glaptop2.roam.corp.google.com
State RFC, archived
Delegated to: David Miller
Headers show

Commit Message

Eric Dumazet Nov. 12, 2015, 5:26 p.m. UTC
On Thu, 2015-11-12 at 10:48 +0100, Sabrina Dubroca wrote:
> 2015-11-10, 16:03:52 -0800, Greg Kroah-Hartman wrote:
> > On Tue, Nov 10, 2015 at 05:59:26PM -0600, Josh Hunt wrote:
> > > On Thu, Oct 29, 2015 at 5:00 AM, Sabrina Dubroca <sd@queasysnail.net> wrote:
> > > > 2015-10-15, 14:25:03 +0200, Sabrina Dubroca wrote:
> > > >> Without this length argument, we can read past the end of the iovec in
> > > >> memcpy_toiovec because we have no way of knowing the total length of the
> > > >> iovec's buffers.
> > > >>
> > > >> This is needed for stable kernels where 89c22d8c3b27 ("net: Fix skb
> > > >> csum races when peeking") has been backported but that don't have the
> > > >> ioviter conversion, which is almost all the stable trees <= 3.18.
> > > >>
> > > >> This also fixes a kernel crash for NFS servers when the client uses
> > > >>  -onfsvers=3,proto=udp to mount the export.
> > > >>
> > > >> Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
> > > >> Reviewed-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
> > > >
> > > > Fixes CVE-2015-8019.
> > > > http://www.openwall.com/lists/oss-security/2015/10/29/1
> > > >
> > > > --
> > > > Sabrina
> > > > --
> > > > To unsubscribe from this list: send the line "unsubscribe netdev" in
> > > > the body of a message to majordomo@vger.kernel.org
> > > > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > > 
> > > Greg
> > > 
> > > Do you have this in your queue? I saw a few other stables pick this
> > > up, but haven't seen it in 3.14 or 3.18 yet. It wasn't clear to me if
> > > this had been fully reviewed yet.
> > 
> > I rely on Dave to package up networking stable patches and forward them
> > on to me, that's why you haven't seen it be picked up yet.
> > 
> > thanks,
> > 
> > greg k-h
> 
> David, can you queue this up?
> 

Note that the following patch (and corresponding part for ipv6) might
also have solve the issue ?

This would supposedly save some cycles when MSG_PEEK is used and user
provides short buffers.



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Comments

Sabrina Dubroca Nov. 16, 2015, 6:06 p.m. UTC | #1
Hello Eric

2015-11-12, 09:26:42 -0800, Eric Dumazet wrote:
> Note that the following patch (and corresponding part for ipv6) might
> also have solve the issue ?
> 
> This would supposedly save some cycles when MSG_PEEK is used and user
> provides short buffers.

Your patch looks correct to me, feel free to submit it.

Since some stable trees already include my patch, maybe it should be
reverted there to keep all trees in sync and ease future backports?


Thanks,

Patch
diff mbox

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 24ec14f9825c..387acab1ab5c 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1272,6 +1272,7 @@  int udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
 	int err;
 	int is_udplite = IS_UDPLITE(sk);
 	bool slow;
+	bool checksum_valid = false;
 
 	if (flags & MSG_ERRQUEUE)
 		return ip_recv_error(sk, msg, len, addr_len);
@@ -1296,11 +1297,12 @@  try_again:
 	 */
 
 	if (copied < ulen || UDP_SKB_CB(skb)->partial_cov) {
-		if (udp_lib_checksum_complete(skb))
+		checksum_valid = !udp_lib_checksum_complete(skb);
+		if (!checksum_valid)
 			goto csum_copy_err;
 	}
 
-	if (skb_csum_unnecessary(skb))
+	if (checksum_valid || skb_csum_unnecessary(skb))
 		err = skb_copy_datagram_msg(skb, sizeof(struct udphdr),
 					    msg, copied);
 	else {