Commit 67e89ac3 authored by Joe Stringer's avatar Joe Stringer Committed by Alexei Starovoitov

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: default avatarJoe Stringer <joe@wand.net.nz>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 1ae80cf3
...@@ -4821,9 +4821,12 @@ static const struct bpf_func_proto bpf_lwt_seg6_adjust_srh_proto = { ...@@ -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, static struct sock *sk_lookup(struct net *net, struct bpf_sock_tuple *tuple,
struct sk_buff *skb, u8 family, u8 proto) struct sk_buff *skb, u8 family, u8 proto)
{ {
int dif = skb->dev->ifindex;
bool refcounted = false; bool refcounted = false;
struct sock *sk = NULL; struct sock *sk = NULL;
int dif = 0;
if (skb->dev)
dif = skb->dev->ifindex;
if (family == AF_INET) { if (family == AF_INET) {
__be32 src4 = tuple->ipv4.saddr; __be32 src4 = tuple->ipv4.saddr;
......
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