| Message ID | 1371497679-14314-2-git-send-email-pablo@netfilter.org |
|---|---|
| State | Accepted |
| Headers | show |
Hello, On Mon, 17 Jun 2013, Pablo Neira Ayuso wrote: > In (bc6bcb5 netfilter: xt_TCPOPTSTRIP: fix possible mangling beyond > packet boundary), the use of tcp_hdr was introduced. However, we > cannot assume that skb->transport_header is set for non-local packets. It is hidden also in tcp_hdrlen() which is used here. > Cc: Florian Westphal <fw@strlen.de> > Reported-by: Phil Oester <kernel@linuxace.com> > Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> > --- > net/netfilter/xt_TCPOPTSTRIP.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/net/netfilter/xt_TCPOPTSTRIP.c b/net/netfilter/xt_TCPOPTSTRIP.c > index 1eb1a44..b68fa19 100644 > --- a/net/netfilter/xt_TCPOPTSTRIP.c > +++ b/net/netfilter/xt_TCPOPTSTRIP.c > @@ -48,11 +48,13 @@ tcpoptstrip_mangle_packet(struct sk_buff *skb, > return NF_DROP; > > len = skb->len - tcphoff; > - if (len < (int)sizeof(struct tcphdr) || > - tcp_hdr(skb)->doff * 4 > len) > + if (len < (int)sizeof(struct tcphdr)) > return NF_DROP; > > tcph = (struct tcphdr *)(skb_network_header(skb) + tcphoff); > + if (tcph->doff * 4 > len) We can save tcph->doff * 4 in a var and use it instead of tcp_hdrlen. BTW, optlen() touches opt[offset+1] unsafely when i == tcp_hdrlen(skb) - 1. > + return NF_DROP; > + > opt = (u_int8_t *)tcph; > > /* > -- > 1.7.10.4 Regards -- Julian Anastasov <ja@ssi.bg> -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/netfilter/xt_TCPOPTSTRIP.c b/net/netfilter/xt_TCPOPTSTRIP.c index 1eb1a44..b68fa19 100644 --- a/net/netfilter/xt_TCPOPTSTRIP.c +++ b/net/netfilter/xt_TCPOPTSTRIP.c @@ -48,11 +48,13 @@ tcpoptstrip_mangle_packet(struct sk_buff *skb, return NF_DROP; len = skb->len - tcphoff; - if (len < (int)sizeof(struct tcphdr) || - tcp_hdr(skb)->doff * 4 > len) + if (len < (int)sizeof(struct tcphdr)) return NF_DROP; tcph = (struct tcphdr *)(skb_network_header(skb) + tcphoff); + if (tcph->doff * 4 > len) + return NF_DROP; + opt = (u_int8_t *)tcph; /*
In (bc6bcb5 netfilter: xt_TCPOPTSTRIP: fix possible mangling beyond packet boundary), the use of tcp_hdr was introduced. However, we cannot assume that skb->transport_header is set for non-local packets. Cc: Florian Westphal <fw@strlen.de> Reported-by: Phil Oester <kernel@linuxace.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> --- net/netfilter/xt_TCPOPTSTRIP.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)