diff options
| author | Jozsef Kadlecsik <kadlec@blackhole.kfki.hu> | 2012-04-03 22:02:01 +0200 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2012-10-17 03:50:04 +0100 |
| commit | ffb364427629d467e0087c36ba9edcfd94032327 (patch) | |
| tree | d5a939f48af3b56934c79a7bb99caec86c27dd7a /net/ipv4 | |
| parent | e489fbf44709bc4e2e82bd0a1389b47228847a41 (diff) | |
netfilter: nf_ct_ipv4: packets with wrong ihl are invalid
commit 07153c6ec074257ade76a461429b567cff2b3a1e upstream.
It was reported that the Linux kernel sometimes logs:
klogd: [2629147.402413] kernel BUG at net / netfilter /
nf_conntrack_proto_tcp.c: 447!
klogd: [1072212.887368] kernel BUG at net / netfilter /
nf_conntrack_proto_tcp.c: 392
ipv4_get_l4proto() in nf_conntrack_l3proto_ipv4.c and tcp_error() in
nf_conntrack_proto_tcp.c should catch malformed packets, so the errors
at the indicated lines - TCP options parsing - should not happen.
However, tcp_error() relies on the "dataoff" offset to the TCP header,
calculated by ipv4_get_l4proto(). But ipv4_get_l4proto() does not check
bogus ihl values in IPv4 packets, which then can slip through tcp_error()
and get caught at the TCP options parsing routines.
The patch fixes ipv4_get_l4proto() by invalidating packets with bogus
ihl value.
The patch closes netfilter bugzilla id 771.
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c index de9da21113a1..d7d63f410495 100644 --- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c +++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c @@ -84,6 +84,14 @@ static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff, *dataoff = nhoff + (iph->ihl << 2); *protonum = iph->protocol; + /* Check bogus IP headers */ + if (*dataoff > skb->len) { + pr_debug("nf_conntrack_ipv4: bogus IPv4 packet: " + "nhoff %u, ihl %u, skblen %u\n", + nhoff, iph->ihl << 2, skb->len); + return -NF_ACCEPT; + } + return NF_ACCEPT; } |