[IPV6]: Fix the return value of get destination options with NULL data pointer

If we pass NULL data buffer to getsockopt(), it will return 0,
and the option length is set to -EFAULT:
    getsockopt(sk, IPPROTO_IPV6, IPV6_DSTOPTS, NULL, &len);

This is because ipv6_getsockopt_sticky() will return -EFAULT or
-EINVAL if some error occur.

This patch fix this problem.

Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 56d55fecf8ec49d49a79e804b0129e8570441df5..aa7bedf780e53cd6641e2a4831e00e27f867d902 100644 (file)
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -975,6 +975,9 @@ static int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
                len = ipv6_getsockopt_sticky(sk, np->opt,
                                             optname, optval, len);
                release_sock(sk);
+               /* check if ipv6_getsockopt_sticky() returns err code */
+               if (len < 0)
+                       return len;
                return put_user(len, optlen);
        }