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

[ Upstream commit 68c6beb373955da0886d8f4f5995b3922ceda4be ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/socket.c b/net/socket.c
index 9f7d6263f7fa..921d1a55c32d 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -215,12 +215,13 @@ 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))