From 4a0851b8b57ec8c873e336d3ac24fb6593ab1c86 Mon Sep 17 00:00:00 2001 From: JP Abgrall Date: Thu, 29 Sep 2011 15:36:49 -0700 Subject: [PATCH] netfilter: ipv6: fix crash caused by ipv6_find_hdr() When calling: ipv6_find_hdr(skb, &thoff, -1, NULL) on a fragmented packet, thoff would be left with a random value causing callers to read random memory offsets with: skb_header_pointer(skb, thoff, ...) Now we force ipv6_find_hdr() to return a failure in this case. Calling: ipv6_find_hdr(skb, &thoff, -1, &fragoff) will set fragoff as expected, and not return a failure. Change-Id: Ib474e8a4267dd2b300feca325811330329684a88 Signed-off-by: JP Abgrall --- net/ipv6/exthdrs_core.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/net/ipv6/exthdrs_core.c b/net/ipv6/exthdrs_core.c index 5c5d23e59da5..835ec57c233b 100644 --- a/net/ipv6/exthdrs_core.c +++ b/net/ipv6/exthdrs_core.c @@ -166,15 +166,15 @@ EXPORT_SYMBOL_GPL(ipv6_find_tlv); * to explore inner IPv6 header, eg. ICMPv6 error messages. * * If target header is found, its offset is set in *offset and return protocol - * number. Otherwise, return -1. + * number. Otherwise, return -ENOENT or -EBADMSG. * * If the first fragment doesn't contain the final protocol header or * NEXTHDR_NONE it is considered invalid. * * Note that non-1st fragment is special case that "the protocol number * of last header" is "next header" field in Fragment header. In this case, - * *offset is meaningless and fragment offset is stored in *fragoff if fragoff - * isn't NULL. + * *offset is meaningless. If fragoff is not NULL, the fragment offset is + * stored in *fragoff; if it is NULL, return -EINVAL. * * if flags is not NULL and it's a fragment, then the frag flag * IP6_FH_F_FRAG will be set. If it's an AH header, the @@ -253,9 +253,12 @@ int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset, if (target < 0 && ((!ipv6_ext_hdr(hp->nexthdr)) || hp->nexthdr == NEXTHDR_NONE)) { - if (fragoff) + if (fragoff) { *fragoff = _frag_off; - return hp->nexthdr; + return hp->nexthdr; + } else { + return -EINVAL; + } } return -ENOENT; } -- 2.20.1