ipv4: check optlen for IP_MULTICAST_IF option

Due to man page of setsockopt, if optlen is not valid, kernel should return
-EINVAL. But a simple testcase as following, errno is 0, which means setsockopt
is successful.
	addr.s_addr = inet_addr("192.1.2.3");
	setsockopt(s, IPPROTO_IP, IP_MULTICAST_IF, &addr, 1);
	printf("errno is %d\n", errno);

Xiaotian Feng([email protected]) caught the bug. We fix it firstly checking
the availability of optlen and then dealing with the logic like other options.

Reported-by: Xiaotian Feng <[email protected]>
Signed-off-by: Shan Wei <[email protected]>
Acked-by: Alexey Kuznetsov <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

0 files changed, 0 insertions, 0 deletions