Commit 67e89ac3 authored Oct 12, 2018 by Joe Stringer Committed by Alexei Starovoitov Oct 13, 2018

bpf: Fix dev pointer dereference from sk_skb



Dan Carpenter reports:

The patch 6acc9b43: "bpf: Add helper to retrieve socket in BPF"
from Oct 2, 2018, leads to the following Smatch complaint:

    net/core/filter.c:4893 bpf_sk_lookup()
    error: we previously assumed 'skb->dev' could be null (see line 4885)

Fix this issue by checking skb->dev before using it.

Signed-off-by: Joe Stringer <joe@wand.net.nz>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

parent 1ae80cf3

net/core/filter.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -4821,9 +4821,12 @@ static const struct bpf_func_proto bpf_lwt_seg6_adjust_srh_proto = {
		static struct sock sk_lookup(struct net net, struct bpf_sock_tuple *tuple,
		struct sk_buff *skb, u8 family, u8 proto)
		{
		int dif = skb->dev->ifindex;
		bool refcounted = false;
		struct sock *sk = NULL;
		int dif = 0;

		if (skb->dev)
		dif = skb->dev->ifindex;

		if (family == AF_INET) {
		__be32 src4 = tuple->ipv4.saddr;