From b90cd7b9d0baab2e8176d9cca5f18a592ef16063 Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Tue, 22 Oct 2013 00:07:47 +0200 Subject: [PATCH] inet: fix possible memory corruption with UDP_CORK and UFO [ This is a simplified -stable version of a set of upstream commits. ] This is a replacement patch only for stable which does fix the problems handled by the following two commits in -net: "ip_output: do skb ufo init for peeked non ufo skb as well" (e93b7d748be887cd7639b113ba7d7ef792a7efb9) "ip6_output: do skb ufo init for peeked non ufo skb as well" (c547dbf55d5f8cf615ccc0e7265e98db27d3fb8b) Three frames are written on a corked udp socket for which the output netdevice has UFO enabled. If the first and third frame are smaller than the mtu and the second one is bigger, we enqueue the second frame with skb_append_datato_frags without initializing the gso fields. This leads to the third frame appended regulary and thus constructing an invalid skb. This fixes the problem by always using skb_append_datato_frags as soon as the first frag got enqueued to the skb without marking the packet as SKB_GSO_UDP. The problem with only two frames for ipv6 was fixed by "ipv6: udp packets following an UFO enqueued packet need also be handled by UFO" (2811ebac2521ceac84f2bdae402455baa6a7fb47). Signed-off-by: Hannes Frederic Sowa Cc: Jiri Pirko Cc: Eric Dumazet Cc: David Miller Signed-off-by: Greg Kroah-Hartman --- include/linux/skbuff.h | 5 +++++ net/ipv4/ip_output.c | 2 +- net/ipv6/ip6_output.c | 2 +- 3 files changed, 7 insertions(+), 2 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index dec1748..eaf6027 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -1308,6 +1308,11 @@ static inline int skb_pagelen(const struct sk_buff *skb) return len + skb_headlen(skb); } +static inline bool skb_has_frags(const struct sk_buff *skb) +{ + return skb_shinfo(skb)->nr_frags; +} + /** * __skb_fill_page_desc - initialise a paged fragment in an skb * @skb: buffer containing fragment to be initialised diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index ec2d430..6ca5873 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -844,7 +844,7 @@ static int __ip_append_data(struct sock *sk, csummode = CHECKSUM_PARTIAL; cork->length += length; - if (((length > mtu) || (skb && skb_is_gso(skb))) && + if (((length > mtu) || (skb && skb_has_frags(skb))) && (sk->sk_protocol == IPPROTO_UDP) && (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) { err = ip_ufo_append_data(sk, queue, getfrag, from, length, diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 44ffdb9..12ef531 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -1250,7 +1250,7 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to, skb = skb_peek_tail(&sk->sk_write_queue); cork->length += length; if (((length > mtu) || - (skb && skb_is_gso(skb))) && + (skb && skb_has_frags(skb))) && (sk->sk_protocol == IPPROTO_UDP) && (rt->dst.dev->features & NETIF_F_UFO)) { err = ip6_ufo_append_data(sk, getfrag, from, length, -- 2.7.4