4.4-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 @@ -873,7 +873,9 @@ static int nfc_genl_activate_target(stru u32 device_idx, target_idx, protocol; int rc; - 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; device_idx = nla_get_u32(info->attrs[NFC_ATTR_DEVICE_INDEX]);