5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Alexey Kashavkin akashavkin@gmail.com
[ Upstream commit 6edd78af9506bb182518da7f6feebd75655d9a0e ]
There is an incorrect calculation in the offset variable which causes the nft_skb_copy_to_reg() function to always return -EFAULT. Adding the start variable is redundant. In the __ip_options_compile() function the correct offset is specified when finding the function. There is no need to add the size of the iphdr structure to the offset.
Fixes: dbb5281a1f84 ("netfilter: nf_tables: add support for matching IPv4 options") Signed-off-by: Alexey Kashavkin akashavkin@gmail.com Reviewed-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/netfilter/nft_exthdr.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c index ca268293cfa12..de43abf6d1191 100644 --- a/net/netfilter/nft_exthdr.c +++ b/net/netfilter/nft_exthdr.c @@ -83,7 +83,6 @@ static int ipv4_find_option(struct net *net, struct sk_buff *skb, unsigned char optbuf[sizeof(struct ip_options) + 40]; struct ip_options *opt = (struct ip_options *)optbuf; struct iphdr *iph, _iph; - unsigned int start; bool found = false; __be32 info; int optlen; @@ -91,7 +90,6 @@ static int ipv4_find_option(struct net *net, struct sk_buff *skb, iph = skb_header_pointer(skb, 0, sizeof(_iph), &_iph); if (!iph) return -EBADMSG; - start = sizeof(struct iphdr);
optlen = iph->ihl * 4 - (int)sizeof(struct iphdr); if (optlen <= 0) @@ -101,7 +99,7 @@ static int ipv4_find_option(struct net *net, struct sk_buff *skb, /* Copy the options since __ip_options_compile() modifies * the options. */ - if (skb_copy_bits(skb, start, opt->__data, optlen)) + if (skb_copy_bits(skb, sizeof(struct iphdr), opt->__data, optlen)) return -EBADMSG; opt->optlen = optlen;
@@ -116,18 +114,18 @@ static int ipv4_find_option(struct net *net, struct sk_buff *skb, found = target == IPOPT_SSRR ? opt->is_strictroute : !opt->is_strictroute; if (found) - *offset = opt->srr + start; + *offset = opt->srr; break; case IPOPT_RR: if (!opt->rr) break; - *offset = opt->rr + start; + *offset = opt->rr; found = true; break; case IPOPT_RA: if (!opt->router_alert) break; - *offset = opt->router_alert + start; + *offset = opt->router_alert; found = true; break; default: