llc: Improve setsockopt() handling of malformed user input

copy_from_sockptr() is used incorrectly: return value is the number of
bytes that could not be copied. Since it's deprecated, switch to
copy_safe_from_sockptr().

Note: Keeping the `optlen != sizeof(int)` check as copy_safe_from_sockptr()
by itself would also accept optlen > sizeof(int). Which would allow a more
lenient handling of inputs.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Suggested-by: David Wei <dw@davidwei.uk>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c
index 4eb52add7103b0f83d6fe7318abf1d1af533d254..0259cde394ba09795a6bf0d44c4ea6767e200aea 100644 (file)
--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -1098,7 +1098,7 @@ static int llc_ui_setsockopt(struct socket *sock, int level, int optname,
        lock_sock(sk);
        if (unlikely(level != SOL_LLC || optlen != sizeof(int)))
                goto out;
-       rc = copy_from_sockptr(&opt, optval, sizeof(opt));
+       rc = copy_safe_from_sockptr(&opt, sizeof(opt), optval, optlen);
        if (rc)
                goto out;
        rc = -EINVAL;