From 8743d499a59c3d6a7c743861fd3baf06ed5fe763 Mon Sep 17 00:00:00 2001 From: Bruce Richardson Date: Mon, 17 Dec 2018 15:50:04 +0000 Subject: [PATCH] net: fix underflow for checksum of invalid IPv4 packets If we receive a packet with an invalid IP header, where the total packet length is reported as less than the IP header length, we would end up getting an underflow in the length subtraction. This could cause us to checksum e.g. 4GB of data in the case where the result of the subtraction was -1. We fix this by having the function return 0 - an invalid sum - when the length is less than the header length. Fixes: af75078fece3 ("first public release") Fixes: 6006818cfb26 ("net: new checksum functions") Cc: stable@dpdk.org Signed-off-by: Bruce Richardson Acked-by: Hemant Agrawal --- lib/librte_net/rte_ip.h | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/lib/librte_net/rte_ip.h b/lib/librte_net/rte_ip.h index f2a8904a2a..f9b9090904 100644 --- a/lib/librte_net/rte_ip.h +++ b/lib/librte_net/rte_ip.h @@ -310,16 +310,20 @@ rte_ipv4_phdr_cksum(const struct ipv4_hdr *ipv4_hdr, uint64_t ol_flags) * @param l4_hdr * The pointer to the beginning of the L4 header. * @return - * The complemented checksum to set in the IP packet. + * The complemented checksum to set in the IP packet + * or 0 on error */ static inline uint16_t rte_ipv4_udptcp_cksum(const struct ipv4_hdr *ipv4_hdr, const void *l4_hdr) { uint32_t cksum; - uint32_t l4_len; + uint32_t l3_len, l4_len; + + l3_len = rte_be_to_cpu_16(ipv4_hdr->total_length); + if (l3_len < sizeof(struct ipv4_hdr)) + return 0; - l4_len = (uint32_t)(rte_be_to_cpu_16(ipv4_hdr->total_length) - - sizeof(struct ipv4_hdr)); + l4_len = l3_len - sizeof(struct ipv4_hdr); cksum = rte_raw_cksum(l4_hdr, l4_len); cksum += rte_ipv4_phdr_cksum(ipv4_hdr, 0); -- 2.20.1