ath10k: add missing sanity check on diag download

ath10k_hw_diag_fast_download() generally has good boundary checking, but
it misses verifying that the next metadata header actually fits in the
remaining buffer space. Add such a check.

Fixes: 39501ea64116 ("ath10k: download firmware via diag Copy Engine for QCA6174 and QCA9377.")
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ath/ath10k/hw.c

@@ -1044,6 +1044,12 @@ int ath10k_hw_diag_fast_download(struct ath10k *ar,
 	left = length - sizeof(*hdr);
 
 	while (left > 0) {
+		if (left < sizeof(*metadata)) {
+			ath10k_warn(ar, "firmware segment is truncated: %d\n",
+				    left);
+			ret = -EINVAL;
+			break;
+		}
 		base_addr = __le32_to_cpu(metadata->addr);
 		base_len = __le32_to_cpu(metadata->length);
 		buf = metadata->data;