net/tap: add buffer overflow checks before checksum

The checksum calculation APIs take only the packet headers pointers as
parameters, so they assume that the lengths reported in those headers
are correct. However, a malicious packet could claim to be far larger
than it is, so we need to check the header lengths in the driver before
calling the checksum API.

A better fix would be to allow the lengths to be passed into the API
function, but that would be an API break, so fixing in TAP driver for
now.

Fixes: 8ae3023387e9 ("net/tap: add Rx/Tx checksum offload support")
Cc: stable@dpdk.org
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>
Acked-by: Keith Wiles <keith.wiles@intel.com>

diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c
index 49afd38..0ec030b 100644 (file)
--- a/drivers/net/tap/rte_eth_tap.c
+++ b/drivers/net/tap/rte_eth_tap.c
@@ -281,13 +281,27 @@ tap_verify_csum(struct rte_mbuf *mbuf)
                l3_len = 4 * (iph->version_ihl & 0xf);
                if (unlikely(l2_len + l3_len > rte_pktmbuf_data_len(mbuf)))
                        return;
+               /* check that the total length reported by header is not
+                * greater than the total received size
+                */
+               if (l2_len + rte_be_to_cpu_16(iph->total_length) >
+                               rte_pktmbuf_data_len(mbuf))
+                       return;
 
                cksum = ~rte_raw_cksum(iph, l3_len);
                mbuf->ol_flags |= cksum ?
                        PKT_RX_IP_CKSUM_BAD :
                        PKT_RX_IP_CKSUM_GOOD;
        } else if (l3 == RTE_PTYPE_L3_IPV6) {
+               struct ipv6_hdr *iph = l3_hdr;
+
                l3_len = sizeof(struct ipv6_hdr);
+               /* check that the total length reported by header is not
+                * greater than the total received size
+                */
+               if (l2_len + l3_len + rte_be_to_cpu_16(iph->payload_len) >
+                               rte_pktmbuf_data_len(mbuf))
+                       return;
        } else {
                /* IPv6 extensions are not supported */
                return;