[PATCH] nfc: Ensure presence of required attributes in the deactivate_target handler

[PATCH] nfc: Ensure presence of required attributes in the deactivate_target handler

[Young Xiao]

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@gmail.com>
---
 net/nfc/netlink.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/nfc/netlink.c b/net/nfc/netlink.c
index 04a8e47..89d885d 100644
--- a/net/nfc/netlink.c
+++ b/net/nfc/netlink.c
@@ -923,7 +923,8 @@ static int nfc_genl_deactivate_target(struct sk_buff *skb,
 	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]);
-- 
2.7.4

Re: [PATCH] nfc: Ensure presence of required attributes in the deactivate_target handler

[David Miller]

From: Young Xiao <92siuyang@gmail.com>
Date: Fri, 14 Jun 2019 15:13:02 +0800

> 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@gmail.com>

Applied and queued up for -stable, thanks.