wifi: ath9k: reject short WMI command responses

ath9k_wmi_rsp_callback() removes the validated WMI header and copies
the number of bytes expected by the waiting command into its response
buffer. A device response shorter than that expectation can therefore
be read beyond the skb payload.

Record -EMSGSIZE for a short response, complete the waiter, and return
the stored status from the command path. This also prevents callers from
consuming stale response bytes as a successful reply.

Fixes: fb9987d0f7 ("ath9k_htc: Support for AR9271 chipset.")
Assisted-by: LLM
Signed-off-by: Pengpeng Hou <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jeff Johnson <[email protected]>

drivers/net/wireless/ath/ath9k/wmi.c

@@ -206,9 +206,16 @@ static void ath9k_wmi_rsp_callback(struct wmi *wmi, struct sk_buff *skb)
 {
 	skb_pull(skb, sizeof(struct wmi_cmd_hdr));
 
-	if (wmi->cmd_rsp_buf != NULL && wmi->cmd_rsp_len != 0)
+	if (wmi->cmd_rsp_buf && wmi->cmd_rsp_len) {
+		if (skb->len < wmi->cmd_rsp_len) {
+			wmi->cmd_rsp_status = -EMSGSIZE;
+			goto complete;
+		}
 		memcpy(wmi->cmd_rsp_buf, skb->data, wmi->cmd_rsp_len);
+	}
+	wmi->cmd_rsp_status = 0;
 
+complete:
 	complete(&wmi->cmd_wait);
 }
 
@@ -300,6 +307,7 @@ static int ath9k_wmi_cmd_issue(struct wmi *wmi,
 	/* record the rsp buffer and length */
 	wmi->cmd_rsp_buf = rsp_buf;
 	wmi->cmd_rsp_len = rsp_len;
+	wmi->cmd_rsp_status = 0;
 
 	wmi->last_seq_id = wmi->tx_seq_id;
 	spin_unlock_irqrestore(&wmi->wmi_lock, flags);
@@ -356,9 +364,13 @@ int ath9k_wmi_cmd(struct wmi *wmi, enum wmi_cmd_id cmd_id,
 		return -ETIMEDOUT;
 	}
 
+	spin_lock_irqsave(&wmi->wmi_lock, flags);
+	ret = wmi->cmd_rsp_status;
+	spin_unlock_irqrestore(&wmi->wmi_lock, flags);
+
 	mutex_unlock(&wmi->op_mutex);
 
-	return 0;
+	return ret;
 
 out:
 	ath_dbg(common, WMI, "WMI failure for: %s\n", wmi_cmd_to_name(cmd_id));

drivers/net/wireless/ath/ath9k/wmi.h

@@ -157,6 +157,7 @@ struct wmi {
 	u16 tx_seq_id;
 	u8 *cmd_rsp_buf;
 	u32 cmd_rsp_len;
+	int cmd_rsp_status;
 	bool stopped;
 
 	struct list_head pending_tx_events;