[PATCH v2 2/2] wifi: brcmfmac: validate msgbuf flowring IDs before use

[Can Peng <pengcan@kylinos.cn>]

Firmware messages carry flow_ring_id values which brcmfmac converts
to an internal flowid by subtracting
BRCMF_H2D_MSGRING_FLOWRING_IDSTART. The resulting value is used as
a bit index in txstatus_done_map and as an array index into
msgbuf->flowrings and the flowring state.

Validate the firmware supplied flow_ring_id before using it. This
prevents flow_ring_id values below BRCMF_H2D_MSGRING_FLOWRING_IDSTART
from underflowing and rejects values outside msgbuf->max_flowrings.

In the tx status path, complete the packet with an error after
removing a valid packet id so the skb is not leaked when the flow
ring id is invalid.

Fixes: 9a1bb60250d2 ("brcmfmac: Adding msgbuf protocol.")
Cc: stable@vger.kernel.org
Signed-off-by: Can Peng <pengcan@kylinos.cn>
---
 .../broadcom/brcm80211/brcmfmac/msgbuf.c      | 46 ++++++++++++++++---
 1 file changed, 40 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/msgbuf.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/msgbuf.c
index 9c41e4a35815..959659bfea99 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/msgbuf.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/msgbuf.c
@@ -548,6 +548,28 @@ brcmf_msgbuf_remove_flowring(struct brcmf_msgbuf *msgbuf, u16 flowid)
 	brcmf_flowring_delete(msgbuf->flow, flowid);
 }
 
+static bool brcmf_msgbuf_get_flowid(struct brcmf_msgbuf *msgbuf,
+				    u16 flow_ring_id, u16 *flowid)
+{
+	u32 id = flow_ring_id;
+
+	if (id < BRCMF_H2D_MSGRING_FLOWRING_IDSTART) {
+		bphy_err(msgbuf->drvr, "invalid flowring id %u\n",
+			 flow_ring_id);
+		return false;
+	}
+
+	id -= BRCMF_H2D_MSGRING_FLOWRING_IDSTART;
+	if (id >= msgbuf->max_flowrings) {
+		bphy_err(msgbuf->drvr, "invalid flowring id %u\n",
+			 flow_ring_id);
+		return false;
+	}
+
+	*flowid = id;
+	return true;
+}
+
 static struct brcmf_msgbuf_work_item *
 brcmf_msgbuf_dequeue_work(struct brcmf_msgbuf *msgbuf)
 {
@@ -855,17 +877,23 @@ brcmf_msgbuf_process_txstatus(struct brcmf_msgbuf *msgbuf, void *buf)
 	struct msgbuf_tx_status *tx_status;
 	u32 idx;
 	struct sk_buff *skb;
+	u16 flow_ring_id;
 	u16 flowid;
 
 	tx_status = (struct msgbuf_tx_status *)buf;
 	idx = le32_to_cpu(tx_status->msg.request_id) - 1;
-	flowid = le16_to_cpu(tx_status->compl_hdr.flow_ring_id);
-	flowid -= BRCMF_H2D_MSGRING_FLOWRING_IDSTART;
+	flow_ring_id = le16_to_cpu(tx_status->compl_hdr.flow_ring_id);
 	skb = brcmf_msgbuf_get_pktid(msgbuf->drvr->bus_if->dev,
 				     msgbuf->tx_pktids, idx);
 	if (!skb)
 		return;
 
+	if (!brcmf_msgbuf_get_flowid(msgbuf, flow_ring_id, &flowid)) {
+		brcmf_txfinalize(brcmf_get_ifp(msgbuf->drvr, tx_status->msg.ifidx),
+				 skb, false);
+		return;
+	}
+
 	set_bit(flowid, msgbuf->txstatus_done_map);
 	commonring = msgbuf->flowrings[flowid];
 	atomic_dec(&commonring->outstanding_tx);
@@ -1204,13 +1232,16 @@ brcmf_msgbuf_process_flow_ring_create_response(struct brcmf_msgbuf *msgbuf,
 	struct msgbuf_flowring_create_resp *flowring_create_resp;
 	u16 status;
 	u16 flowid;
+	u16 flow_ring_id;
 
 	flowring_create_resp = (struct msgbuf_flowring_create_resp *)buf;
 
-	flowid = le16_to_cpu(flowring_create_resp->compl_hdr.flow_ring_id);
-	flowid -= BRCMF_H2D_MSGRING_FLOWRING_IDSTART;
+	flow_ring_id = le16_to_cpu(flowring_create_resp->compl_hdr.flow_ring_id);
 	status =  le16_to_cpu(flowring_create_resp->compl_hdr.status);
 
+	if (!brcmf_msgbuf_get_flowid(msgbuf, flow_ring_id, &flowid))
+		return;
+
 	if (status) {
 		bphy_err(drvr, "Flowring creation failed, code %d\n", status);
 		brcmf_msgbuf_remove_flowring(msgbuf, flowid);
@@ -1232,13 +1263,16 @@ brcmf_msgbuf_process_flow_ring_delete_response(struct brcmf_msgbuf *msgbuf,
 	struct msgbuf_flowring_delete_resp *flowring_delete_resp;
 	u16 status;
 	u16 flowid;
+	u16 flow_ring_id;
 
 	flowring_delete_resp = (struct msgbuf_flowring_delete_resp *)buf;
 
-	flowid = le16_to_cpu(flowring_delete_resp->compl_hdr.flow_ring_id);
-	flowid -= BRCMF_H2D_MSGRING_FLOWRING_IDSTART;
+	flow_ring_id = le16_to_cpu(flowring_delete_resp->compl_hdr.flow_ring_id);
 	status =  le16_to_cpu(flowring_delete_resp->compl_hdr.status);
 
+	if (!brcmf_msgbuf_get_flowid(msgbuf, flow_ring_id, &flowid))
+		return;
+
 	if (status) {
 		bphy_err(drvr, "Flowring deletion failed, code %d\n", status);
 		brcmf_flowring_delete(msgbuf->flow, flowid);
-- 
2.53.0