net: clamp ->msg_namelen instead of returning an error

If kmsg->msg_namelen > sizeof(struct sockaddr_storage) then in the
original code that would lead to memory corruption in the kernel if you
had audit configured.  If you didn't have audit configured it was
harmless.

There are some programs such as beta versions of Ruby which use too
large of a buffer and returning an error code breaks them.  We should
clamp the ->msg_namelen value instead.

Fixes: 1661bf364ae9 ("net: heap overflow in __audit_sockaddr()")
Reported-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Tested-by: Eric Wong <normalperson@yhbt.net>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/compat.c b/net/compat.c
index 618c6a8a911b65c9a406ba5d7d0e221cb124960e..dd32e34c1e2c9481aa2db3c37437ef0d85ba5277 100644 (file)
--- a/net/compat.c
+++ b/net/compat.c
@@ -72,7 +72,7 @@ int get_compat_msghdr(struct msghdr *kmsg, struct compat_msghdr __user *umsg)
            __get_user(kmsg->msg_flags, &umsg->msg_flags))
                return -EFAULT;
        if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
-               return -EINVAL;
+               kmsg->msg_namelen = sizeof(struct sockaddr_storage);
        kmsg->msg_name = compat_ptr(tmp1);
        kmsg->msg_iov = compat_ptr(tmp2);
        kmsg->msg_control = compat_ptr(tmp3);

diff --git a/net/socket.c b/net/socket.c
index 0b18693f2be6deb2f6f6b6bbf99aa131c767e830..e83c416708af5554f89c98723bba150b8750b3f0 100644 (file)
--- a/net/socket.c
+++ b/net/socket.c
@@ -1973,7 +1973,7 @@ static int copy_msghdr_from_user(struct msghdr *kmsg,
        if (copy_from_user(kmsg, umsg, sizeof(struct msghdr)))
                return -EFAULT;
        if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
-               return -EINVAL;
+               kmsg->msg_namelen = sizeof(struct sockaddr_storage);
        return 0;
 }