Commit 405c92f7 authored Oct 27, 2015 by Hannes Frederic Sowa Committed by David S. Miller Nov 01, 2015

ipv6: 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.

Fixes: commit 32dce968 ("ipv6: Allow for partial checksums on non-ufo packets")
See-also: commit 72e843bb ("ipv6: ip6_fragment() should check CHECKSUM_PARTIAL")
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>

parent 682b1a9d

net/ipv6/ip6_output.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -603,6 +603,10 @@ int ip6_fragment(struct net net, struct sock sk, struct sk_buff *skb,
		frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr,
		&ipv6_hdr(skb)->saddr);

		if (skb->ip_summed == CHECKSUM_PARTIAL &&
		(err = skb_checksum_help(skb)))
		goto fail;

		hroom = LL_RESERVED_SPACE(rt->dst.dev);
		if (skb_has_frag_list(skb)) {
		int first_len = skb_pagelen(skb);
		@@ -731,10 +735,6 @@ int ip6_fragment(struct net net, struct sock sk, struct sk_buff *skb,
		}

		slow_path:
		if ((skb->ip_summed == CHECKSUM_PARTIAL) &&
		skb_checksum_help(skb))
		goto fail;

		left = skb->len - hlen; /* Space per frame */
		ptr = hlen; /* Where to start from */