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Commit dbd3393c authored by Hannes Frederic Sowa's avatar Hannes Frederic Sowa Committed by David S. Miller
Browse files

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: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d749c9cb

net/ipv4/ip_output.c

+5 −3
Original line number Diff line number Diff line
@@ -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 @@ int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, 
	}



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 */