diff options
| author | Davide Caratti <dcaratti@redhat.com> | 2017-05-18 18:01:43 +0200 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2017-05-23 22:54:14 +0200 |
| commit | f3c0eb05e258c6a48c2d1ef2fa71ffb6ff63cd18 (patch) | |
| tree | 7397ca4a6e3c9d980a8a599b070056f407124296 /net | |
| parent | 6d18c732b95c0a9d35e9f978b4438bba15412284 (diff) | |
netfilter: conntrack: fix false CRC32c mismatch using paged skb
sctp_compute_cksum() implementation assumes that at least the SCTP header
is in the linear part of skb: modify conntrack error callback to avoid
false CRC32c mismatch, if the transport header is partially/entirely paged.
Fixes: cf6e007eef83 ("netfilter: conntrack: validate SCTP crc32c in PREROUTING")
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/netfilter/nf_conntrack_proto_sctp.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/net/netfilter/nf_conntrack_proto_sctp.c b/net/netfilter/nf_conntrack_proto_sctp.c index 13875d599a85..1c5b14a6cab3 100644 --- a/net/netfilter/nf_conntrack_proto_sctp.c +++ b/net/netfilter/nf_conntrack_proto_sctp.c @@ -512,16 +512,19 @@ static int sctp_error(struct net *net, struct nf_conn *tpl, struct sk_buff *skb, u8 pf, unsigned int hooknum) { const struct sctphdr *sh; - struct sctphdr _sctph; const char *logmsg; - sh = skb_header_pointer(skb, dataoff, sizeof(_sctph), &_sctph); - if (!sh) { + if (skb->len < dataoff + sizeof(struct sctphdr)) { logmsg = "nf_ct_sctp: short packet "; goto out_invalid; } if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING && skb->ip_summed == CHECKSUM_NONE) { + if (!skb_make_writable(skb, dataoff + sizeof(struct sctphdr))) { + logmsg = "nf_ct_sctp: failed to read header "; + goto out_invalid; + } + sh = (const struct sctphdr *)(skb->data + dataoff); if (sh->checksum != sctp_compute_cksum(skb, dataoff)) { logmsg = "nf_ct_sctp: bad CRC "; goto out_invalid; |