[PATCH 3.18 09/60] nfc: Ensure presence of required attributes in the activate_target handler

From: Greg Kroah-Hartman
Date: Tue Jul 25 2017 - 17:38:40 EST


3.18-stable review patch. If anyone has any objections, please let me know.

------------------

From: Mateusz Jurczyk <mjurczyk@xxxxxxxxxx>

commit a0323b979f81ad2deb2c8836eab506534891876a upstream.

Check that the NFC_ATTR_TARGET_INDEX and NFC_ATTR_PROTOCOLS 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: Mateusz Jurczyk <mjurczyk@xxxxxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Samuel Ortiz <sameo@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
net/nfc/netlink.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/net/nfc/netlink.c
+++ b/net/nfc/netlink.c
@@ -899,7 +899,9 @@ static int nfc_genl_llc_get_params(struc
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_TARGET_INDEX] ||
+ !info->attrs[NFC_ATTR_PROTOCOLS])
return -EINVAL;

idx = nla_get_u32(info->attrs[NFC_ATTR_DEVICE_INDEX]);