From: Hannes Frederic Sowa <hannes@stressinduktion.org>
Date: Tue, 27 Oct 2015 21:40:40 +0000 (+0100)
Subject: ipv4: add defensive check for CHECKSUM_PARTIAL skbs in ip_fragment
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=dbd3393c56a8794fe596e7dd20d0efa613b9cf61;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

ipv4: add defensive check for CHECKSUM_PARTIAL skbs in ip_fragment

CHECKSUM_PARTIAL skbs should never arrive in ip_fragment. If we get one
of those warn about them once and handle them gracefully by recalculating
the checksum.

Cc: Eric Dumazet <edumazet@google.com>
Cc: Vlad Yasevich <vyasevich@gmail.com>
Cc: Benjamin Coddington <bcodding@redhat.com>
Cc: Tom Herbert <tom@herbertland.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 0b024178edd3..4233cbe47052 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -533,6 +533,11 @@ int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 
 	dev = rt->dst.dev;
 
+	/* for offloaded checksums cleanup checksum before fragmentation */
+	if (skb->ip_summed == CHECKSUM_PARTIAL &&
+	    (err = skb_checksum_help(skb)))
+		goto fail;
+
 	/*
 	 *	Point into the IP datagram header.
 	 */
@@ -657,9 +662,6 @@ slow_path_clean:
 	}
 
 slow_path:
-	/* for offloaded checksums cleanup checksum before fragmentation */
-	if ((skb->ip_summed == CHECKSUM_PARTIAL) && skb_checksum_help(skb))
-		goto fail;
 	iph = ip_hdr(skb);
 
 	left = skb->len - hlen;		/* Space per frame */