[PATCH] nfc: st21nfca: Fix potential buffer overflows in EVT_TRANSACTION

[Denis Efremov <denis.e.efremov@oracle.com>]

From: Jordy Zomer <jordy@pwning.systems>

It appears that there are some buffer overflows in EVT_TRANSACTION.
This happens because the length parameters that are passed to memcpy
come directly from skb->data and are not guarded in any way.

Link: https://lore.kernel.org/all/20220111164451.3232987-1-jordy@pwning.systems/#t
Fixes: 26fc6c7f02cb ("NFC: st21nfca: Add HCI transaction event support")
Cc: stable@vger.kernel.org # 4.0+
Signed-off-by: Jordy Zomer <jordy@pwning.systems>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Denis Efremov <denis.e.efremov@oracle.com>
---
CVE-2022-26490 was assigned to this patch. It looks like it's not in
the stable trees yet. I only added Link:/Fixes:/Cc: stable... to the
commit's message.

 drivers/nfc/st21nfca/se.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/nfc/st21nfca/se.c b/drivers/nfc/st21nfca/se.c
index a43fc4117fa5..c922f10d0d7b 100644
--- a/drivers/nfc/st21nfca/se.c
+++ b/drivers/nfc/st21nfca/se.c
@@ -316,6 +316,11 @@ int st21nfca_connectivity_event_received(struct nfc_hci_dev *hdev, u8 host,
 			return -ENOMEM;
 
 		transaction->aid_len = skb->data[1];
+
+		/* Checking if the length of the AID is valid */
+		if (transaction->aid_len > sizeof(transaction->aid))
+			return -EINVAL;
+
 		memcpy(transaction->aid, &skb->data[2],
 		       transaction->aid_len);
 
@@ -325,6 +330,11 @@ int st21nfca_connectivity_event_received(struct nfc_hci_dev *hdev, u8 host,
 			return -EPROTO;
 
 		transaction->params_len = skb->data[transaction->aid_len + 3];
+
+		/* Total size is allocated (skb->len - 2) minus fixed array members */
+		if (transaction->params_len > ((skb->len - 2) - sizeof(struct nfc_evt_transaction)))
+			return -EINVAL;
+
 		memcpy(transaction->params, skb->data +
 		       transaction->aid_len + 4, transaction->params_len);
 
-- 
2.35.1