From: Martin Faltesek mfaltesek@google.com
[ Upstream commit 0254f31a7df3bb3b90c2d9dd2d4052f7b95eb287 ]
The transaction buffer is allocated by using the size of the packet buf, and subtracting two which seems intended to remove the two tags which are not present in the target structure. This calculation leads to under counting memory because of differences between the packet contents and the target structure. The aid_len field is a u8 in the packet, but a u32 in the structure, resulting in at least 3 bytes always being under counted. Further, the aid data is a variable length field in the packet, but fixed in the structure, so if this field is less than the max, the difference is added to the under counting.
To fix, perform validation checks progressively to safely reach the next field, to determine the size of both buffers and verify both tags. Once all validation checks pass, allocate the buffer and copy the data. This eliminates freeing memory on the error path, as validation checks are moved ahead of memory allocation.
Reported-by: Denis Efremov denis.e.efremov@oracle.com Reviewed-by: Guenter Roeck groeck@google.com Fixes: 5d1ceb7f5e56 ("NFC: st21nfcb: Add HCI transaction event support") Signed-off-by: Martin Faltesek mfaltesek@google.com Reviewed-by: Krzysztof Kozlowski krzysztof.kozlowski@linaro.org Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/nfc/st-nci/se.c | 51 +++++++++++++++++++++++++++++------------ 1 file changed, 36 insertions(+), 15 deletions(-)
diff --git a/drivers/nfc/st-nci/se.c b/drivers/nfc/st-nci/se.c index a915cad909b4..04a2cea6d6b6 100644 --- a/drivers/nfc/st-nci/se.c +++ b/drivers/nfc/st-nci/se.c @@ -312,6 +312,8 @@ static int st_nci_hci_connectivity_event_received(struct nci_dev *ndev, 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);
@@ -325,28 +327,47 @@ static int st_nci_hci_connectivity_event_received(struct nci_dev *ndev, * 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); - if (!transaction) - return -ENOMEM; + aid_len = skb->data[1];
- transaction->aid_len = skb->data[1]; - memcpy(transaction->aid, &skb->data[2], transaction->aid_len); + if (skb->len < aid_len + 4 || + aid_len > sizeof(transaction->aid)) + return -EPROTO;
- /* Check next byte is PARAMETERS tag (82) */ - if (skb->data[transaction->aid_len + 2] != - NFC_EVT_TRANSACTION_PARAMS_TAG) { - devm_kfree(dev, transaction); + 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->params_len = skb->data[transaction->aid_len + 3]; - memcpy(transaction->params, skb->data + - transaction->aid_len + 4, transaction->params_len); + transaction = devm_kzalloc(dev, sizeof(*transaction) + + params_len, GFP_KERNEL); + if (!transaction) + return -ENOMEM; + + transaction->aid_len = aid_len; + transaction->params_len = 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;