The firmware download receive path removes the NCI data header and
reads the helper command before validating the remaining packet length.
A short frame can therefore reach the data access before the malformed
packet is rejected.
Validate the complete helper command length before stripping the NCI
data header.
Fixes: 3194c6870158 ("NFC: nfcmrvl: add firmware download support")
Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
---
drivers/nfc/nfcmrvl/fw_dnld.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/drivers/nfc/nfcmrvl/fw_dnld.c b/drivers/nfc/nfcmrvl/fw_dnld.c
index 2b8f401d8fd7..8b9d5257320d 100644
--- a/drivers/nfc/nfcmrvl/fw_dnld.c
+++ b/drivers/nfc/nfcmrvl/fw_dnld.c
@@ -263,9 +263,14 @@ static int process_state_fw_dnld(struct nfcmrvl_private *priv,
* B8..N: payload
*/
- /* Remove NCI HDR */
- skb_pull(skb, 3);
- if (skb->data[0] != HELPER_CMD_PACKET_FORMAT || skb->len != 5) {
+ if (skb->len != NCI_DATA_HDR_SIZE + 5) {
+ nfc_err(priv->dev, "bad command");
+ return -EINVAL;
+ }
+
+ /* Remove NCI header */
+ skb_pull(skb, NCI_DATA_HDR_SIZE);
+ if (skb->data[0] != HELPER_CMD_PACKET_FORMAT) {
nfc_err(priv->dev, "bad command");
return -EINVAL;
}
--
2.43.0