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. Signed-off-by: Alexey Kashavkin <akashavkin@xxxxxxxxx> --- 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 b8d03364566c..c74012c99125 100644 --- a/net/netfilter/nft_exthdr.c +++ b/net/netfilter/nft_exthdr.c @@ -85,7 +85,6 @@ 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; @@ -93,7 +92,6 @@ 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) @@ -103,7 +101,7 @@ 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; @@ -118,18 +116,18 @@ 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: -- 2.39.2
