diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2015-03-12 18:22:59 -0500 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-03-12 23:05:04 -0400 |
| commit | 76fecd8275be6de76513430e7526825944ab932f (patch) | |
| tree | c04917753aa8f8cd07d54140c9580af45c7f5dd8 | |
| parent | 2c29b2354a06f42493ddd2a5eb65962981e666ed (diff) | |
mpls: In mpls_egress verify the packet length.
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>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/mpls/af_mpls.c | 17 |
1 files changed, 16 insertions, 1 deletions
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, |