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| author | Eric Dumazet <edumazet@google.com> | 2013-12-11 08:10:05 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-12-11 16:10:14 -0500 |
| commit | 610438b74496b2986a9025f8e23c134cb638e338 (patch) | |
| tree | a04eec671093bb727ba8aacb8da6a289e6b77f45 /net/ipv4/udp.c | |
| parent | ce232ce01d61b184202bb185103d119820e1260c (diff) | |
| download | lwn-610438b74496b2986a9025f8e23c134cb638e338.tar.gz lwn-610438b74496b2986a9025f8e23c134cb638e338.zip | |
udp: ipv4: fix potential use after free in udp_v4_early_demux()
pskb_may_pull() can reallocate skb->head, we need to move the
initialization of iph and uh pointers after its call.
Fixes: 421b3885bf6d ("udp: ipv4: Add udp early demux")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Shawn Bohrer <sbohrer@rgmadvisors.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/udp.c')
| -rw-r--r-- | net/ipv4/udp.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 2e2aecbe22c4..16d246a51a02 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1909,17 +1909,20 @@ static struct sock *__udp4_lib_demux_lookup(struct net *net, void udp_v4_early_demux(struct sk_buff *skb) { - const struct iphdr *iph = ip_hdr(skb); - const struct udphdr *uh = udp_hdr(skb); + struct net *net = dev_net(skb->dev); + const struct iphdr *iph; + const struct udphdr *uh; struct sock *sk; struct dst_entry *dst; - struct net *net = dev_net(skb->dev); int dif = skb->dev->ifindex; /* validate the packet */ if (!pskb_may_pull(skb, skb_transport_offset(skb) + sizeof(struct udphdr))) return; + iph = ip_hdr(skb); + uh = udp_hdr(skb); + if (skb->pkt_type == PACKET_BROADCAST || skb->pkt_type == PACKET_MULTICAST) sk = __udp4_lib_mcast_demux_lookup(net, uh->dest, iph->daddr, |