wifi: ath9k: add range check for conn_rsp_epid in htc_connect_service()

I found the following bug in my fuzzer:

  UBSAN: array-index-out-of-bounds in drivers/net/wireless/ath/ath9k/htc_hst.c:26:51
  index 255 is out of range for type 'htc_endpoint [22]'
  CPU: 0 UID: 0 PID: 8 Comm: kworker/0:0 Not tainted 6.11.0-rc6-dirty torvalds#14
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
  Workqueue: events request_firmware_work_func
  Call Trace:
   <TASK>
   dump_stack_lvl+0x180/0x1b0
   __ubsan_handle_out_of_bounds+0xd4/0x130
   htc_issue_send.constprop.0+0x20c/0x230
   ? _raw_spin_unlock_irqrestore+0x3c/0x70
   ath9k_wmi_cmd+0x41d/0x610
   ? mark_held_locks+0x9f/0xe0
   ...

Since this bug has been confirmed to be caused by insufficient verification
of conn_rsp_epid, I think it would be appropriate to add a range check for
conn_rsp_epid to htc_connect_service() to prevent the bug from occurring.

Fixes: fb9987d ("ath9k_htc: Support for AR9271 chipset.")
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://patch.msgid.link/20240909103855.68006-1-aha310510@gmail.com

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

@@ -294,6 +294,9 @@ int htc_connect_service(struct htc_target *target,
 		return -ETIMEDOUT;
 	}
 
+	if (target->conn_rsp_epid < 0 || target->conn_rsp_epid >= ENDPOINT_MAX)
+		return -EINVAL;
+
 	*conn_rsp_epid = target->conn_rsp_epid;
 	return 0;
 err: