[patch added to the 3.12 stable tree] NFC: microread: Potential overflows in microread_target_discovered()

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From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

This patch has been added to the 3.12 stable tree. If you have any
objections, please let us know.

===============

commit d07f1e8600ccb885c8f4143402b8912f7d827bcb upstream.

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@xxxxxxxxxx>
Signed-off-by: Samuel Ortiz <sameo@xxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 drivers/nfc/microread/microread.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/nfc/microread/microread.c b/drivers/nfc/microread/microread.c
index cdb9f6de132a..562fa6b0cc62 100644
--- 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;
-- 
2.1.1

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