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: Willy Tarreau <w@1wt.eu>

diff --git a/net/socket.c b/net/socket.c
index 06e8f3d1db2f68906a869d49e5ad815ce5aeaea9..11bad156278414223db184cfa3ba4b45302c46dc 100644 (file)
--- a/net/socket.c
+++ b/net/socket.c
@@ -216,12 +216,13 @@ int move_addr_to_user(struct sockaddr *kaddr, int klen, void __user *uaddr,
        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))