| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 21/48] ipv4: fix use-after-free in ip_cmsg_recv_dstaddr() | Date | Thu, 18 Oct 2018 19:54:56 +0200 |
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4.4-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet <edumazet@google.com>
[ Upstream commit 64199fc0a46ba211362472f7f942f900af9492fd ]
Caching ip_hdr(skb) before a call to pskb_may_pull() is buggy, do not do it.
Fixes: 2efd4fca703a ("ip: in cmsg IP(V6)_ORIGDSTADDR call pskb_may_pull") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Willem de Bruijn <willemb@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Acked-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/ipv4/ip_sockglue.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
--- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -134,7 +134,6 @@ static void ip_cmsg_recv_security(struct static void ip_cmsg_recv_dstaddr(struct msghdr *msg, struct sk_buff *skb) { struct sockaddr_in sin; - const struct iphdr *iph = ip_hdr(skb); __be16 *ports; int end; @@ -149,7 +148,7 @@ static void ip_cmsg_recv_dstaddr(struct ports = (__be16 *)skb_transport_header(skb); sin.sin_family = AF_INET; - sin.sin_addr.s_addr = iph->daddr; + sin.sin_addr.s_addr = ip_hdr(skb)->daddr; sin.sin_port = ports[1]; memset(sin.sin_zero, 0, sizeof(sin.sin_zero));
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