drm/i915/uc: Fix two issues with over-size firmware files

In the case where a firmware file is too large (e.g. someone
downloaded a web page ASCII dump from github...), the firmware object
is released but the pointer is not zerod. If no other firmware file
was found then release would be called again leading to a double kfree.

Also, the size check was only being applied to the initial firmware
load not any of the subsequent attempts. So move the check into a
wrapper that is used for all loads.

Fixes: 01624116 ("drm/i915/uc: use different ggtt pin offsets for uc loads")
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Alan Previn <alan.previn.teres.alexis@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: "Thomas Hellström" <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221221193031.687266-4-John.C.Harrison@Intel.com

drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c

@@ -675,6 +675,32 @@ static int check_fw_header(struct intel_gt *gt,
 	return 0;
 }
 
+static int try_firmware_load(struct intel_uc_fw *uc_fw, const struct firmware **fw)
+{
+	struct intel_gt *gt = __uc_fw_to_gt(uc_fw);
+	struct device *dev = gt->i915->drm.dev;
+	int err;
+
+	err = firmware_request_nowarn(fw, uc_fw->file_selected.path, dev);
+
+	if (err)
+		return err;
+
+	if ((*fw)->size > INTEL_UC_RSVD_GGTT_PER_FW) {
+		drm_err(&gt->i915->drm,
+			"%s firmware %s: size (%zuKB) exceeds max supported size (%uKB)\n",
+			intel_uc_fw_type_repr(uc_fw->type), uc_fw->file_selected.path,
+			(*fw)->size / SZ_1K, INTEL_UC_RSVD_GGTT_PER_FW / SZ_1K);
+
+		/* try to find another blob to load */
+		release_firmware(*fw);
+		*fw = NULL;
+		return -ENOENT;
+	}
+
+	return 0;
+}
+
 /**
  * intel_uc_fw_fetch - fetch uC firmware
  * @uc_fw: uC firmware
@@ -688,7 +714,6 @@ int intel_uc_fw_fetch(struct intel_uc_fw *uc_fw)
 	struct intel_gt *gt = __uc_fw_to_gt(uc_fw);
 	struct drm_i915_private *i915 = gt->i915;
 	struct intel_uc_fw_file file_ideal;
-	struct device *dev = i915->drm.dev;
 	struct drm_i915_gem_object *obj;
 	const struct firmware *fw = NULL;
 	bool old_ver = false;
@@ -704,20 +729,9 @@ int intel_uc_fw_fetch(struct intel_uc_fw *uc_fw)
 	__force_fw_fetch_failures(uc_fw, -EINVAL);
 	__force_fw_fetch_failures(uc_fw, -ESTALE);
 
-	err = firmware_request_nowarn(&fw, uc_fw->file_selected.path, dev);
+	err = try_firmware_load(uc_fw, &fw);
 	memcpy(&file_ideal, &uc_fw->file_wanted, sizeof(file_ideal));
 
-	if (!err && fw->size > INTEL_UC_RSVD_GGTT_PER_FW) {
-		drm_err(&i915->drm,
-			"%s firmware %s: size (%zuKB) exceeds max supported size (%uKB)\n",
-			intel_uc_fw_type_repr(uc_fw->type), uc_fw->file_selected.path,
-			fw->size / SZ_1K, INTEL_UC_RSVD_GGTT_PER_FW / SZ_1K);
-
-		/* try to find another blob to load */
-		release_firmware(fw);
-		err = -ENOENT;
-	}
-
 	/* Any error is terminal if overriding. Don't bother searching for older versions */
 	if (err && intel_uc_fw_is_overridden(uc_fw))
 		goto fail;
@@ -738,7 +752,7 @@ int intel_uc_fw_fetch(struct intel_uc_fw *uc_fw)
 			break;
 		}
 
-		err = firmware_request_nowarn(&fw, uc_fw->file_selected.path, dev);
+		err = try_firmware_load(uc_fw, &fw);
 	}
 
 	if (err)