From patchwork Wed Jan 9 16:55:10 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [3.5.y.z, extended, stable] Patch "ipv4: ip_check_defrag must not modify skb before unsharing" has been added to staging queue Date: Wed, 09 Jan 2013 06:55:10 -0000 From: Herton Ronaldo Krzesinski X-Patchwork-Id: 210763 Message-Id: <1357750510-24745-1-git-send-email-herton.krzesinski@canonical.com> To: Johannes Berg Cc: Eric Leblond , "David S. Miller" , stable@vger.kernel.org, kernel-team@lists.ubuntu.com This is a note to let you know that I have just added a patch titled ipv4: ip_check_defrag must not modify skb before unsharing to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Herton ------ >From 89420415417b8ef6684d71992b62567d04638cbb Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Sun, 9 Dec 2012 23:41:06 +0000 Subject: [PATCH] ipv4: ip_check_defrag must not modify skb before unsharing commit 1bf3751ec90cc3174e01f0d701e8449ce163d113 upstream. ip_check_defrag() might be called from af_packet within the RX path where shared SKBs are used, so it must not modify the input SKB before it has unshared it for defragmentation. Use skb_copy_bits() to get the IP header and only pull in everything later. The same is true for the other caller in macvlan as it is called from dev->rx_handler which can also get a shared SKB. Reported-by: Eric Leblond Cc: stable@vger.kernel.org Signed-off-by: Johannes Berg Signed-off-by: David S. Miller Signed-off-by: Herton Ronaldo Krzesinski --- net/ipv4/ip_fragment.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) -- 1.7.9.5 diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c index 9dbd3dd..3fdcdb8 100644 --- a/net/ipv4/ip_fragment.c +++ b/net/ipv4/ip_fragment.c @@ -698,28 +698,27 @@ EXPORT_SYMBOL(ip_defrag); struct sk_buff *ip_check_defrag(struct sk_buff *skb, u32 user) { - const struct iphdr *iph; + struct iphdr iph; u32 len; if (skb->protocol != htons(ETH_P_IP)) return skb; - if (!pskb_may_pull(skb, sizeof(struct iphdr))) + if (!skb_copy_bits(skb, 0, &iph, sizeof(iph))) return skb; - iph = ip_hdr(skb); - if (iph->ihl < 5 || iph->version != 4) + if (iph.ihl < 5 || iph.version != 4) return skb; - if (!pskb_may_pull(skb, iph->ihl*4)) - return skb; - iph = ip_hdr(skb); - len = ntohs(iph->tot_len); - if (skb->len < len || len < (iph->ihl * 4)) + + len = ntohs(iph.tot_len); + if (skb->len < len || len < (iph.ihl * 4)) return skb; - if (ip_is_fragment(ip_hdr(skb))) { + if (ip_is_fragment(&iph)) { skb = skb_share_check(skb, GFP_ATOMIC); if (skb) { + if (!pskb_may_pull(skb, iph.ihl*4)) + return skb; if (pskb_trim_rcsum(skb, len)) return skb; memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));