net: socket: error on a negative msg_namelen

[ Upstream commit dbb490b96584d4e958533fb637f08b557f505657 ]

When copying in a struct msghdr from the user, if the user has set the
msg_namelen parameter to a negative value it gets clamped to a valid
size due to a comparison between signed and unsigned values.

Ensure the syscall errors when the user passes in a negative value.

Signed-off-by: Matthew Leach <matthew.leach@arm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/socket.c b/net/socket.c
index ac72efc..fc90b4f 100644 (file)
--- a/net/socket.c
+++ b/net/socket.c
@@ -1964,6 +1964,10 @@ static int copy_msghdr_from_user(struct msghdr *kmsg,
 {
        if (copy_from_user(kmsg, umsg, sizeof(struct msghdr)))
                return -EFAULT;
+
+       if (kmsg->msg_namelen < 0)
+               return -EINVAL;
+
        if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
                kmsg->msg_namelen = sizeof(struct sockaddr_storage);
        return 0;