Re: [PATCH] net/neighbour: fix potential null pointer deference

[Konstantin Khlebnikov]

On 31.05.2019 11:29, Young Xiao wrote:

There is a possible null pointer deference bugs in neigh_fill_info(),
which is similar to the bug which was fixed in commit 6adc5fd6a142
("net/neighbour: fix crash at dumping device-agnostic proxy entries").

Have you seen this in real life?
I see nobody who could produce neighbour with null device pointer._

Signed-off-by: Young Xiao <92siuy...@gmail.com>
---
  net/core/neighbour.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index dfa8710..33c3ff1 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -2440,7 +2440,7 @@ static int neigh_fill_info(struct sk_buff *skb, struct 
neighbour *neigh,
        ndm->ndm_pad2    = 0;
        ndm->ndm_flags        = neigh->flags;
        ndm->ndm_type         = neigh->type;
-       ndm->ndm_ifindex = neigh->dev->ifindex;
+       ndm->ndm_ifindex = neigh->dev ? neigh->dev->ifindex : 0;

if (nla_put(skb, NDA_DST, neigh->tbl->key_len, neigh->primary_key))

                goto nla_put_failure;