Merge branch 'nfc-st-nci-restructure-validating-logic-in-evt_transaction'
Martin Faltesek says:
====================
nfc: st-nci: Restructure validating logic in EVT_TRANSACTION
These are the same 3 patches that were applied in st21nfca here:
https://lore.kernel.org/netdev/20220607025729.1673212-1-mfaltesek@google.com
with a couple minor differences.
st-nci has nearly identical code to that of st21nfca for EVT_TRANSACTION,
except that there are two extra validation checks that are not present
in the st-nci code.
The 3/3 patch as coded for st21nfca pulls those checks in, bringing both
drivers into parity.
====================
Link: https://lore.kernel.org/r/20221122004246.4186422-1-mfaltesek@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
diff --git a/drivers/nfc/st-nci/se.c b/drivers/nfc/st-nci/se.c
index 7764b1a..ec87dd2 100644
--- a/drivers/nfc/st-nci/se.c
+++ b/drivers/nfc/st-nci/se.c
@@ -312,6 +312,8 @@
int r = 0;
struct device *dev = &ndev->nfc_dev->dev;
struct nfc_evt_transaction *transaction;
+ u32 aid_len;
+ u8 params_len;
pr_debug("connectivity gate event: %x\n", event);
@@ -325,26 +327,47 @@
* Description Tag Length
* AID 81 5 to 16
* PARAMETERS 82 0 to 255
+ *
+ * The key differences are aid storage length is variably sized
+ * in the packet, but fixed in nfc_evt_transaction, and that
+ * the aid_len is u8 in the packet, but u32 in the structure,
+ * and the tags in the packet are not included in
+ * nfc_evt_transaction.
+ *
+ * size(b): 1 1 5-16 1 1 0-255
+ * offset: 0 1 2 aid_len + 2 aid_len + 3 aid_len + 4
+ * mem name: aid_tag(M) aid_len aid params_tag(M) params_len params
+ * example: 0x81 5-16 X 0x82 0-255 X
*/
- if (skb->len < NFC_MIN_AID_LENGTH + 2 &&
- skb->data[0] != NFC_EVT_TRANSACTION_AID_TAG)
+ if (skb->len < 2 || skb->data[0] != NFC_EVT_TRANSACTION_AID_TAG)
return -EPROTO;
- transaction = devm_kzalloc(dev, skb->len - 2, GFP_KERNEL);
+ aid_len = skb->data[1];
+
+ if (skb->len < aid_len + 4 ||
+ aid_len > sizeof(transaction->aid))
+ return -EPROTO;
+
+ params_len = skb->data[aid_len + 3];
+
+ /* Verify PARAMETERS tag is (82), and final check that there is
+ * enough space in the packet to read everything.
+ */
+ if (skb->data[aid_len + 2] != NFC_EVT_TRANSACTION_PARAMS_TAG ||
+ skb->len < aid_len + 4 + params_len)
+ return -EPROTO;
+
+ transaction = devm_kzalloc(dev, sizeof(*transaction) +
+ params_len, GFP_KERNEL);
if (!transaction)
return -ENOMEM;
- transaction->aid_len = skb->data[1];
- memcpy(transaction->aid, &skb->data[2], transaction->aid_len);
+ transaction->aid_len = aid_len;
+ transaction->params_len = params_len;
- /* Check next byte is PARAMETERS tag (82) */
- if (skb->data[transaction->aid_len + 2] !=
- NFC_EVT_TRANSACTION_PARAMS_TAG)
- return -EPROTO;
-
- transaction->params_len = skb->data[transaction->aid_len + 3];
- memcpy(transaction->params, skb->data +
- transaction->aid_len + 4, transaction->params_len);
+ memcpy(transaction->aid, &skb->data[2], aid_len);
+ memcpy(transaction->params, &skb->data[aid_len + 4],
+ params_len);
r = nfc_se_transaction(ndev->nfc_dev, host, transaction);
break;
