| Message ID | 87a8zhztpo.fsf@x220.int.ebiederm.org |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: ebiederm@xmission.com (Eric W. Biederman) Date: Thu, 12 Mar 2015 18:22:59 -0500 > > Reobert Shearman noticed that mpls_egress is failing to verify that > the bytes to be examined are in fact present in the packet before > mpls_egress reads those bytes. > > As suggested by David Miller reduce this to a single pskb_may_pull > call so that we don't do unnecessary work in the fast path. > > Reported-by: Robert Shearman <rshearma@brocade.com> > Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Perfect, applied, thanks! -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c index 0ad8f7141be2..db8a2ea6d4de 100644 --- a/net/mpls/af_mpls.c +++ b/net/mpls/af_mpls.c @@ -92,9 +92,24 @@ static bool mpls_egress(struct mpls_route *rt, struct sk_buff *skb, * The strange cases if we choose to support them will require * manual configuration. */ - struct iphdr *hdr4 = ip_hdr(skb); + struct iphdr *hdr4; bool success = true; + /* The IPv4 code below accesses through the IPv4 header + * checksum, which is 12 bytes into the packet. + * The IPv6 code below accesses through the IPv6 hop limit + * which is 8 bytes into the packet. + * + * For all supported cases there should always be at least 12 + * bytes of packet data present. The IPv4 header is 20 bytes + * without options and the IPv6 header is always 40 bytes + * long. + */ + if (!pskb_may_pull(skb, 12)) + return false; + + /* Use ip_hdr to find the ip protocol version */ + hdr4 = ip_hdr(skb); if (hdr4->version == 4) { skb->protocol = htons(ETH_P_IP); csum_replace2(&hdr4->check,
Reobert Shearman noticed that mpls_egress is failing to verify that the bytes to be examined are in fact present in the packet before mpls_egress reads those bytes. As suggested by David Miller reduce this to a single pskb_may_pull call so that we don't do unnecessary work in the fast path. Reported-by: Robert Shearman <rshearma@brocade.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> --- net/mpls/af_mpls.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-)