Prefer pskb_may_pull() to avoid a stack canary in raw6_local_deliver(). Note: skb->head can change, hence we reload ip6h pointer in ipv6_raw_deliver() $ scripts/bloat-o-meter -t vmlinux.old vmlinux.new add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-86 (-86) Function old new delta raw6_local_deliver 780 694 -86 Total: Before=24889784, After=24889698, chg -0.00% Signed-off-by: Eric Dumazet --- net/ipv6/raw.c | 32 ++++++++++++++++---------------- 1 file changed, 16 insertions(+), 16 deletions(-) diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c index ee6beba03e9b498c8ea5b9e5834e26251f81e958..27a2680591684eb2cad011e63cdaf396e79c0d77 100644 --- a/net/ipv6/raw.c +++ b/net/ipv6/raw.c @@ -90,23 +90,24 @@ EXPORT_SYMBOL_GPL(raw_v6_match); * 0 - deliver * 1 - block */ -static int icmpv6_filter(const struct sock *sk, const struct sk_buff *skb) +static int icmpv6_filter(const struct sock *sk, struct sk_buff *skb) { - struct icmp6hdr _hdr; const struct icmp6hdr *hdr; + const __u32 *data; + unsigned int type; /* We require only the four bytes of the ICMPv6 header, not any * additional bytes of message body in "struct icmp6hdr". */ - hdr = skb_header_pointer(skb, skb_transport_offset(skb), - ICMPV6_HDRLEN, &_hdr); - if (hdr) { - const __u32 *data = &raw6_sk(sk)->filter.data[0]; - unsigned int type = hdr->icmp6_type; + if (!pskb_may_pull(skb, ICMPV6_HDRLEN)) + return 1; - return (data[type >> 5] & (1U << (type & 31))) != 0; - } - return 1; + hdr = (struct icmp6hdr *)skb->data; + type = hdr->icmp6_type; + + data = &raw6_sk(sk)->filter.data[0]; + + return (data[type >> 5] & (1U << (type & 31))) != 0; } #if IS_ENABLED(CONFIG_IPV6_MIP6) @@ -141,15 +142,13 @@ EXPORT_SYMBOL(rawv6_mh_filter_unregister); static bool ipv6_raw_deliver(struct sk_buff *skb, int nexthdr) { struct net *net = dev_net(skb->dev); - const struct in6_addr *saddr; - const struct in6_addr *daddr; + const struct ipv6hdr *ip6h; struct hlist_head *hlist; - struct sock *sk; bool delivered = false; + struct sock *sk; __u8 hash; - saddr = &ipv6_hdr(skb)->saddr; - daddr = saddr + 1; + ip6h = ipv6_hdr(skb); hash = raw_hashfunc(net, nexthdr); hlist = &raw_v6_hashinfo.ht[hash]; @@ -157,7 +156,7 @@ static bool ipv6_raw_deliver(struct sk_buff *skb, int nexthdr) sk_for_each_rcu(sk, hlist) { int filtered; - if (!raw_v6_match(net, sk, nexthdr, daddr, saddr, + if (!raw_v6_match(net, sk, nexthdr, &ip6h->daddr, &ip6h->saddr, inet6_iif(skb), inet6_sdif(skb))) continue; @@ -171,6 +170,7 @@ static bool ipv6_raw_deliver(struct sk_buff *skb, int nexthdr) switch (nexthdr) { case IPPROTO_ICMPV6: filtered = icmpv6_filter(sk, skb); + ip6h = ipv6_hdr(skb); break; #if IS_ENABLED(CONFIG_IPV6_MIP6) -- 2.53.0.rc2.204.g2597b5adb4-goog