NFC: microread: Potential overflows in microread_target_discovered()

Smatch says that skb->data is untrusted so we need to check to make sure
that the memcpy() doesn't overflow.

Fixes: cfad1ba87150 ('NFC: Initial support for Inside Secure microread')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

diff --git a/drivers/nfc/microread/microread.c b/drivers/nfc/microread/microread.c
index f868333..963a4a5 100644 (file)
--- a/drivers/nfc/microread/microread.c
+++ b/drivers/nfc/microread/microread.c
@@ -501,9 +501,13 @@ static void microread_target_discovered(struct nfc_hci_dev *hdev, u8 gate,
                targets->sens_res =
                         be16_to_cpu(*(u16 *)&skb->data[MICROREAD_EMCF_A_ATQA]);
                targets->sel_res = skb->data[MICROREAD_EMCF_A_SAK];
-               memcpy(targets->nfcid1, &skb->data[MICROREAD_EMCF_A_UID],
-                      skb->data[MICROREAD_EMCF_A_LEN]);
                targets->nfcid1_len = skb->data[MICROREAD_EMCF_A_LEN];
+               if (targets->nfcid1_len > sizeof(targets->nfcid1)) {
+                       r = -EINVAL;
+                       goto exit_free;
+               }
+               memcpy(targets->nfcid1, &skb->data[MICROREAD_EMCF_A_UID],
+                      targets->nfcid1_len);
                break;
        case MICROREAD_GATE_ID_MREAD_ISO_A_3:
                targets->supported_protocols =
@@ -511,9 +515,13 @@ static void microread_target_discovered(struct nfc_hci_dev *hdev, u8 gate,
                targets->sens_res =
                         be16_to_cpu(*(u16 *)&skb->data[MICROREAD_EMCF_A3_ATQA]);
                targets->sel_res = skb->data[MICROREAD_EMCF_A3_SAK];
-               memcpy(targets->nfcid1, &skb->data[MICROREAD_EMCF_A3_UID],
-                      skb->data[MICROREAD_EMCF_A3_LEN]);
                targets->nfcid1_len = skb->data[MICROREAD_EMCF_A3_LEN];
+               if (targets->nfcid1_len > sizeof(targets->nfcid1)) {
+                       r = -EINVAL;
+                       goto exit_free;
+               }
+               memcpy(targets->nfcid1, &skb->data[MICROREAD_EMCF_A3_UID],
+                      targets->nfcid1_len);
                break;
        case MICROREAD_GATE_ID_MREAD_ISO_B:
                targets->supported_protocols = NFC_PROTO_ISO14443_B_MASK;