We must have an address to lookup otherwise we'll derefence a null pointer in the ndo_fdb_get callbacks. CC: Roopa Prabhu <roopa@xxxxxxxxxxxxxxxxxxx> CC: David Ahern <dsa@xxxxxxxxxxxxxxxxxxx> Reported-by: syzbot+017b1f61c82a1c3e7efd@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 5b2f94b27622 ("net: rtnetlink: support for fdb get") Signed-off-by: Nikolay Aleksandrov <nikolay@xxxxxxxxxxxxxxxxxxx> --- net/core/rtnetlink.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 48f61885fd6f..5ea1bed08ede 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -4104,6 +4104,11 @@ static int rtnl_fdb_get(struct sk_buff *in_skb, struct nlmsghdr *nlh, if (err < 0) return err; + if (!addr) { + NL_SET_ERR_MSG(extack, "Missing lookup address for fdb get request"); + return -EINVAL; + } + if (brport_idx) { dev = __dev_get_by_index(net, brport_idx); if (!dev) { -- 2.19.2