From c562b61ed91605dc0c5790aaf2df09b566df77b6 Mon Sep 17 00:00:00 2001 From: Ben Pfaff Date: Fri, 3 Mar 2017 21:16:17 -0800 Subject: [PATCH] conntrack: Fix checks for TCP, UDP, and IPv6 header sizes. Otherwise a malformed packet could cause a read up to about 40 bytes past the end of the packet. The packet would still likely be dropped because of checksum verification. Reported-by: Bhargava Shastry Signed-off-by: Ben Pfaff Acked-by: Daniele Di Proietto --- lib/conntrack.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/lib/conntrack.c b/lib/conntrack.c index 9bea3d93e4..677c0d2a3c 100644 --- a/lib/conntrack.c +++ b/lib/conntrack.c @@ -568,15 +568,15 @@ extract_l3_ipv6(struct conn_key *key, const void *data, size_t size, const char **new_data) { const struct ovs_16aligned_ip6_hdr *ip6 = data; - uint8_t nw_proto = ip6->ip6_nxt; - uint8_t nw_frag = 0; - if (new_data) { if (OVS_UNLIKELY(size < sizeof *ip6)) { return false; } } + uint8_t nw_proto = ip6->ip6_nxt; + uint8_t nw_frag = 0; + data = ip6 + 1; size -= sizeof *ip6; @@ -623,8 +623,11 @@ check_l4_tcp(const struct conn_key *key, const void *data, size_t size, const void *l3) { const struct tcp_header *tcp = data; - size_t tcp_len = TCP_OFFSET(tcp->tcp_ctl) * 4; + if (size < sizeof *tcp) { + return false; + } + size_t tcp_len = TCP_OFFSET(tcp->tcp_ctl) * 4; if (OVS_UNLIKELY(tcp_len < TCP_HEADER_LEN || tcp_len > size)) { return false; } @@ -637,8 +640,11 @@ check_l4_udp(const struct conn_key *key, const void *data, size_t size, const void *l3) { const struct udp_header *udp = data; - size_t udp_len = ntohs(udp->udp_len); + if (size < sizeof *udp) { + return false; + } + size_t udp_len = ntohs(udp->udp_len); if (OVS_UNLIKELY(udp_len < UDP_HEADER_LEN || udp_len > size)) { return false; }