From: Eric Dumazet Date: Fri, 17 Mar 2017 15:05:28 +0000 (-0700) Subject: sch_dsmark: fix invalid skb_cow() usage X-Git-Tag: v3.2.91~55 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=d940902921d277f53338dddd5068840893e9b372 sch_dsmark: fix invalid skb_cow() usage commit aea92fb2e09e29653b023d4254ac9fbf94221538 upstream. skb_cow(skb, sizeof(ip header)) is not very helpful in this context. First we need to use pskb_may_pull() to make sure the ip header is in skb linear part, then use skb_try_make_writable() to address clones issues. Fixes: 4c30719f4f55 ("[PKT_SCHED] dsmark: handle cloned and non-linear skb's") Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- diff --git a/net/sched/sch_dsmark.c b/net/sched/sch_dsmark.c index d75bfcf972f0..fb24bb4f5818 100644 --- a/net/sched/sch_dsmark.c +++ b/net/sched/sch_dsmark.c @@ -202,9 +202,13 @@ static int dsmark_enqueue(struct sk_buff *skb, struct Qdisc *sch) pr_debug("dsmark_enqueue(skb %p,sch %p,[qdisc %p])\n", skb, sch, p); if (p->set_tc_index) { + int wlen = skb_network_offset(skb); + switch (skb->protocol) { case htons(ETH_P_IP): - if (skb_cow_head(skb, sizeof(struct iphdr))) + wlen += sizeof(struct iphdr); + if (!pskb_may_pull(skb, wlen) || + skb_try_make_writable(skb, wlen)) goto drop; skb->tc_index = ipv4_get_dsfield(ip_hdr(skb)) @@ -212,7 +216,9 @@ static int dsmark_enqueue(struct sk_buff *skb, struct Qdisc *sch) break; case htons(ETH_P_IPV6): - if (skb_cow_head(skb, sizeof(struct ipv6hdr))) + wlen += sizeof(struct ipv6hdr); + if (!pskb_may_pull(skb, wlen) || + skb_try_make_writable(skb, wlen)) goto drop; skb->tc_index = ipv6_get_dsfield(ipv6_hdr(skb))