[PATCH 4.19 09/61] nfc: Ensure presence of required attributes in the deactivate_target handler

[Greg Kroah-Hartman]

From: Young Xiao <92siuyang@xxxxxxxxx>

[ Upstream commit 385097a3675749cbc9e97c085c0e5dfe4269ca51 ]

Check that the NFC_ATTR_TARGET_INDEX attributes (in addition to
NFC_ATTR_DEVICE_INDEX) are provided by the netlink client prior to
accessing them. This prevents potential unhandled NULL pointer dereference
exceptions which can be triggered by malicious user-mode programs,
if they omit one or both of these attributes.

Signed-off-by: Young Xiao <92siuyang@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/nfc/netlink.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/nfc/netlink.c
+++ b/net/nfc/netlink.c
@@ -922,7 +922,8 @@ static int nfc_genl_deactivate_target(st
 	u32 device_idx, target_idx;
 	int rc;
 
-	if (!info->attrs[NFC_ATTR_DEVICE_INDEX])
+	if (!info->attrs[NFC_ATTR_DEVICE_INDEX] ||
+	    !info->attrs[NFC_ATTR_TARGET_INDEX])
 		return -EINVAL;
 
 	device_idx = nla_get_u32(info->attrs[NFC_ATTR_DEVICE_INDEX]);