sock_diag: Fix out-of-bounds access to sock_diag_handlers[]

Userland can send a netlink message requesting SOCK_DIAG_BY_FAMILY
with a family greater or equal then AF_MAX -- the array size of
sock_diag_handlers[]. The current code does not test for this
condition therefore is vulnerable to an out-of-bound access opening
doors for a privilege escalation.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/net/core/sock_diag.c b/net/core/sock_diag.c
index 602cd637182e..750f44f3aa31 100644
--- a/net/core/sock_diag.c
+++ b/net/core/sock_diag.c
@@ -121,6 +121,9 @@ static int __sock_diag_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
         if (nlmsg_len(nlh) < sizeof(*req))
                 return -EINVAL;
 
+        if (req->sdiag_family >= AF_MAX)
+                return -EINVAL;
+
         hndl = sock_diag_lock_handler(req->sdiag_family);
         if (hndl == NULL)
                 err = -ENOENT;