NFC: fix attrs checks in netlink interface

commit 18917d51472fe3b126a3a8f756c6b18085eb8130 upstream.

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: NAndrey Konovalov <andreyknvl@google.com>
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

net/nfc/netlink.c

@@ -981,7 +981,8 @@ 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]);
@@ -1029,7 +1030,8 @@ 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]);