nfc: Ensure presence of NFC_ATTR_FIRMWARE_NAME attribute in nfc_genl_fw_download()

Check that the NFC_ATTR_FIRMWARE_NAME attributes 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.

Similar to commit a0323b979f81 ("nfc: Ensure presence of required attributes in the activate_target handler").

Fixes: 9674da8759df ("NFC: Add firmware upload netlink command")
Signed-off-by: Defang Bo <bodefang@126.com>
Link: https://lore.kernel.org/r/1603107538-4744-1-git-send-email-bodefang@126.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/nfc/netlink.c b/net/nfc/netlink.c
index e894254..8709f3d 100644 (file)
--- a/net/nfc/netlink.c
+++ b/net/nfc/netlink.c
@@ -1217,7 +1217,7 @@ static int nfc_genl_fw_download(struct sk_buff *skb, struct genl_info *info)
        u32 idx;
        char firmware_name[NFC_FIRMWARE_NAME_MAXSIZE + 1];
 
-       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]);