From: Ziyang Xuan Date: Thu, 20 Apr 2023 12:40:35 +0000 (+0800) Subject: ipv4: Fix potential uninit variable access bug in __ip_make_skb() X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=99e5acae193e369b71217efe6f1dad42f3f18815;p=linux.git ipv4: Fix potential uninit variable access bug in __ip_make_skb() Like commit ea30388baebc ("ipv6: Fix an uninit variable access bug in __ip6_make_skb()"). icmphdr does not in skb linear region under the scenario of SOCK_RAW socket. Access icmp_hdr(skb)->type directly will trigger the uninit variable access bug. Use a local variable icmp_type to carry the correct value in different scenarios. Fixes: 96793b482540 ("[IPV4]: Add ICMPMsgStats MIB (RFC 4293)") Reviewed-by: Willem de Bruijn Signed-off-by: Ziyang Xuan Signed-off-by: David S. Miller --- diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 4e4e308c3230a..89bd7872c6290 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -1570,9 +1570,19 @@ struct sk_buff *__ip_make_skb(struct sock *sk, cork->dst = NULL; skb_dst_set(skb, &rt->dst); - if (iph->protocol == IPPROTO_ICMP) - icmp_out_count(net, ((struct icmphdr *) - skb_transport_header(skb))->type); + if (iph->protocol == IPPROTO_ICMP) { + u8 icmp_type; + + /* For such sockets, transhdrlen is zero when do ip_append_data(), + * so icmphdr does not in skb linear region and can not get icmp_type + * by icmp_hdr(skb)->type. + */ + if (sk->sk_type == SOCK_RAW && !inet_sk(sk)->hdrincl) + icmp_type = fl4->fl4_icmp_type; + else + icmp_type = icmp_hdr(skb)->type; + icmp_out_count(net, icmp_type); + } ip_cork_release(cork); out: