[PATCH 4.9 01/14] nfc: st21nfca: Fix potential buffer overflows in EVT_TRANSACTION

Greg Kroah-Hartman
2022-03-25T15:04:52Z

From: Jordy Zomer <jordy@pwning.systems>

commit 4fbcc1a4cb20fe26ad0225679c536c80f1648221 upstream.

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.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/nfc/st21nfca/se.c | 10 ++++++++++
1 file changed, 10 insertions(+)

--- a/drivers/nfc/st21nfca/se.c
+++ b/drivers/nfc/st21nfca/se.c
@@ -330,6 +330,11 @@ int st21nfca_connectivity_event_received
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);

@@ -339,6 +344,11 @@ int st21nfca_connectivity_event_received
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);