bridge: netfilter: fix information leak

Struct tmp is copied from userspace.  It is not checked whether the "name"
field is NULL terminated.  This may lead to buffer overflow and passing
contents of kernel stack as a module name to try_then_request_module() and,
consequently, to modprobe commandline.  It would be seen by all userspace
processes.

Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
static int ebt_compat_entry_padsize(void)
{
	BUILD_BUG_ON(XT_ALIGN(sizeof(struct ebt_entry_match)) <
			COMPAT_XT_ALIGN(sizeof(struct compat_ebt_entry_mwt)));
	return (int) XT_ALIGN(sizeof(struct ebt_entry_match)) -
			COMPAT_XT_ALIGN(sizeof(struct compat_ebt_entry_mwt));
}

static int ebt_compat_entry_padsize(void)
{
	BUILD_BUG_ON(XT_ALIGN(sizeof(struct ebt_entry_match)) <
			COMPAT_XT_ALIGN(sizeof(struct compat_ebt_entry_mwt)));
	return (int) XT_ALIGN(sizeof(struct ebt_entry_match)) -
			COMPAT_XT_ALIGN(sizeof(struct compat_ebt_entry_mwt));
}
