Messages in this thread Patch in this message | | | From | Jordy Zomer <> | Subject | [PATCH] nfc: st21nfca: Fix potential buffer overflows in EVT_TRANSACTION | Date | Wed, 17 Nov 2021 18:17:03 +0100 |
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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.
It would be nice if someone can review and test this patch because I don't own the hardware :)
Signed-off-by: Jordy Zomer <jordy@pwning.systems> --- drivers/nfc/st21nfca/se.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)
diff --git a/drivers/nfc/st21nfca/se.c b/drivers/nfc/st21nfca/se.c index a43fc4117fa5..e3483aca3280 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 +330,14 @@ int st21nfca_connectivity_event_received(struct nfc_hci_dev *hdev, u8 host, return -EPROTO; transaction->params_len = skb->data[transaction->aid_len + 3]; + + // check if the length of the parameters is valid + // we can't use sizeof(transaction->params) because it's + // a flexible array member so we have to check if params_len + // is bigger than the space allocated for the array + 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); -- 2.27.0
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