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| author | Guillaume Nault <gnault@redhat.com> | 2020-10-31 01:07:25 +0100 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2020-11-03 12:55:53 -0800 |
| commit | 0992d67bc2bcd723d57c6ee7883bda4524450179 (patch) | |
| tree | 903f3d2bf87fd50a0bb247d5297435abfdb651e7 /net/mpls | |
| parent | 6d89076e6ef09337a29a7b1ea4fdf2d892be9650 (diff) | |
| download | linux-0992d67bc2bcd723d57c6ee7883bda4524450179.tar.gz linux-0992d67bc2bcd723d57c6ee7883bda4524450179.tar.bz2 linux-0992d67bc2bcd723d57c6ee7883bda4524450179.zip | |
mpls: drop skb's dst in mpls_forward()
Commit 394de110a733 ("net: Added pointer check for
dst->ops->neigh_lookup in dst_neigh_lookup_skb") added a test in
dst_neigh_lookup_skb() to avoid a NULL pointer dereference. The root
cause was the MPLS forwarding code, which doesn't call skb_dst_drop()
on incoming packets. That is, if the packet is received from a
collect_md device, it has a metadata_dst attached to it that doesn't
implement any dst_ops function.
To align the MPLS behaviour with IPv4 and IPv6, let's drop the dst in
mpls_forward(). This way, dst_neigh_lookup_skb() doesn't need to test
->neigh_lookup any more. Let's keep a WARN condition though, to
document the precondition and to ease detection of such problems in the
future.
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Link: https://lore.kernel.org/r/f8c2784c13faa54469a2aac339470b1049ca6b63.1604102750.git.gnault@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/mpls')
| -rw-r--r-- | net/mpls/af_mpls.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c index f2868a8a50c3..47bab701555f 100644 --- a/net/mpls/af_mpls.c +++ b/net/mpls/af_mpls.c @@ -377,6 +377,8 @@ static int mpls_forward(struct sk_buff *skb, struct net_device *dev, if (!pskb_may_pull(skb, sizeof(*hdr))) goto err; + skb_dst_drop(skb); + /* Read and decode the label */ hdr = mpls_hdr(skb); dec = mpls_entry_decode(hdr); |