net: add BUG_ON if kernel advertises msg_namelen > sizeof(struct sockaddr_storage)

In that case it is probable that kernel code overwrote part of the
stack. So we should bail out loudly here.

The BUG_ON may be removed in future if we are sure all protocols are
conformant.

Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/socket.c b/net/socket.c
index fc285564e49ec180e66c70e53f6b72a04cdfcea6..0b18693f2be6deb2f6f6b6bbf99aa131c767e830 100644 (file)
--- a/net/socket.c
+++ b/net/socket.c
@@ -221,12 +221,13 @@ static int move_addr_to_user(struct sockaddr_storage *kaddr, int klen,
        int err;
        int len;
 
+       BUG_ON(klen > sizeof(struct sockaddr_storage));
        err = get_user(len, ulen);
        if (err)
                return err;
        if (len > klen)
                len = klen;
-       if (len < 0 || len > sizeof(struct sockaddr_storage))
+       if (len < 0)
                return -EINVAL;
        if (len) {
                if (audit_sockaddr(klen, kaddr))