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NFC: potential overflows in microread_target_discovered()

PATCH New Dan Carpenter 1 participant 1 message Jan 20, 2014

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Dan Carpenter

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PATCH 1/1 NFC: 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 <[email protected]>

---
Compile tested only.

drivers/nfc/microread/microread.c +6 -2
index f868333271aa..963a4a5dc88e 100644
@@ -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;