[PATCH net 4/5] nfc: st21nfca: validate pipe ids in st21nfca_hci_load_session()

[Joas Antonio dos Santos <joasantonio108@gmail.com>]

st21nfca_hci_load_session() gets the list of open pipes from the
controller and, for each pipe id in it, asks for the pipe information
and records it in hdev->pipes[].  The pipe id is a byte from the
controller and is used as an index into hdev->pipes[], which has
NFC_HCI_MAX_PIPES (128) entries, without any check.  For a pipe id of
128 or more that the controller reports as open on one of the known
gates, the gate id and the controller supplied host id are written past
the end of the array, over the rest of struct nfc_hci_dev (including
the async_cb function pointer) and, for larger ids, past the end of the
object.

The pipe information response is not length checked either, so a
short response is read past its end.

Skip pipe ids that do not fit in hdev->pipes[] and responses that are
shorter than struct st21nfca_pipe_info.

This was pointed out as a pre-existing issue by the sashiko review of an
nfc_hci_create_pipe() fix.

Link: https://lore.kernel.org/all/178952042575.22033.9676833200303972344@kernel.org/
Fixes: 2130fb97fecf ("NFC: st21nfca: Adding support for secure element")
Cc: stable@vger.kernel.org
Signed-off-by: Joas Antonio dos Santos <joasantonio108@gmail.com>
Assisted-by: Yaga Agent HackerSec Claude:claude-opus-5-5
---
 drivers/nfc/st21nfca/core.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/nfc/st21nfca/core.c b/drivers/nfc/st21nfca/core.c
index b5c1ca3ac..88856c26c 100644
--- a/drivers/nfc/st21nfca/core.c
+++ b/drivers/nfc/st21nfca/core.c
@@ -147,12 +147,20 @@ static int st21nfca_hci_load_session(struct nfc_hci_dev *hdev)
 	/* Complete the existing gate_pipe table */
 	for (i = 0; i < skb_pipe_list->len; i++) {
 		pipe_info[2] = skb_pipe_list->data[i];
+		if (pipe_info[2] >= NFC_HCI_MAX_PIPES)
+			continue;
+
 		r = nfc_hci_send_cmd(hdev, ST21NFCA_DEVICE_MGNT_GATE,
 					ST21NFCA_DM_GETINFO, pipe_info,
 					sizeof(pipe_info), &skb_pipe_info);
 		if (r)
 			continue;
 
+		if (skb_pipe_info->len < sizeof(*info)) {
+			kfree_skb(skb_pipe_info);
+			continue;
+		}
+
 		/*
 		 * Match pipe ID and gate ID
 		 * Output format from ST21NFC_DM_GETINFO is:
-- 
2.43.0