NFC: fix attrs checks in netlink interface

nfc_genl_deactivate_target() relies on the NFC_ATTR_TARGET_INDEX
attribute being present, but doesn't check whether it is actually
provided by the user. Same goes for nfc_genl_fw_download() and
NFC_ATTR_FIRMWARE_NAME.

This patch adds appropriate checks.

Found with syzkaller.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/nfc/netlink.c

@@ -970,7 +970,8 @@ static int nfc_genl_dep_link_down(struct sk_buff *skb, struct genl_info *info)
 	int rc;
 	u32 idx;
 
-	if (!info->attrs[NFC_ATTR_DEVICE_INDEX])
+	if (!info->attrs[NFC_ATTR_DEVICE_INDEX] ||
+	    !info->attrs[NFC_ATTR_TARGET_INDEX])
 		return -EINVAL;
 
 	idx = nla_get_u32(info->attrs[NFC_ATTR_DEVICE_INDEX]);
@@ -1018,7 +1019,8 @@ static int nfc_genl_llc_get_params(struct sk_buff *skb, struct genl_info *info)
 	struct sk_buff *msg = NULL;
 	u32 idx;
 
-	if (!info->attrs[NFC_ATTR_DEVICE_INDEX])
+	if (!info->attrs[NFC_ATTR_DEVICE_INDEX] ||
+	    !info->attrs[NFC_ATTR_FIRMWARE_NAME])
 		return -EINVAL;
 
 	idx = nla_get_u32(info->attrs[NFC_ATTR_DEVICE_INDEX]);