soc: qcom: mdt_loader: Detect truncated read of segments

Given that no validation of how much data the firmware loader read in
for a given segment truncated segment files would best case result in a
hash verification failure, without any indication of what went wrong.

Improve this by validating that the firmware loader did return the
amount of data requested.

Fixes: 445c2410a4 ("soc: qcom: mdt_loader: Use request_firmware_into_buf()")
Reviewed-by: Sibi Sankar <sibis@codeaurora.org>
Link: https://lore.kernel.org/r/20210107232526.716989-1-bjorn.andersson@linaro.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/soc/qcom/mdt_loader.c

@@ -261,6 +261,15 @@ static int __qcom_mdt_load(struct device *dev, const struct firmware *fw,
 				break;
 			}
 
+			if (seg_fw->size != phdr->p_filesz) {
+				dev_err(dev,
+					"failed to load segment %d from truncated file %s\n",
+					i, fw_name);
+				release_firmware(seg_fw);
+				ret = -EINVAL;
+				break;
+			}
+
 			release_firmware(seg_fw);
 		}