drm/i915/panic: fix panic structure allocation memory leak

Separating the panic allocation from framebuffer allocation in commit
729c5f7ffa83 ("drm/{i915,xe}/panic: move framebuffer allocation where it
belongs") failed to deallocate the panic structure anywhere.

The fix is two-fold. First, free the panic structure in
intel_user_framebuffer_destroy() in the general case. Second, move the
panic allocation later to intel_framebuffer_init() to not leak the panic
structure in error paths (if any, now or later) between
intel_framebuffer_alloc() and intel_framebuffer_init().

v2: Rebase

Fixes: 729c5f7ffa83 ("drm/{i915,xe}/panic: move framebuffer allocation where it belongs")
Cc: Jocelyn Falempe <[e-mail]>
Cc: Maarten Lankhorst <[e-mail]>
Reported-by: Michał Grzelak <[e-mail]>
Suggested-by: Ville Syrjälä <[e-mail]>
Tested-by: Michał Grzelak <[e-mail]> # v1
Reviewed-by: Jocelyn Falempe <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jani Nikula <[e-mail]>
(cherry picked from commit 8f8ef09fcf6a3b00369bfc704e8f68d7474eca94)
Signed-off-by: Rodrigo Vivi <[e-mail]>

drivers/gpu/drm/i915/display/intel_fb.c

···
 
 	intel_frontbuffer_put(intel_fb->frontbuffer);
 
+	kfree(intel_fb->panic);
 	kfree(intel_fb);
 }
 
···
 	struct intel_display *display = to_intel_display(obj->dev);
 	struct drm_framebuffer *fb = &intel_fb->base;
 	u32 max_stride;
-	int ret = -EINVAL;
+	int ret;
 	int i;
+
+	intel_fb->panic = intel_panic_alloc();
+	if (!intel_fb->panic)
+		return -ENOMEM;
 
 	/*
 	 * intel_frontbuffer_get() must be done before
 	 * intel_fb_bo_framebuffer_init() to avoid set_tiling vs. addfb race.
 	 */
 	intel_fb->frontbuffer = intel_frontbuffer_get(obj);
-	if (!intel_fb->frontbuffer)
-		return -ENOMEM;
+	if (!intel_fb->frontbuffer) {
+		ret = -ENOMEM;
+		goto err_free_panic;
+	}
 
 	ret = intel_fb_bo_framebuffer_init(fb, obj, mode_cmd);
 	if (ret)
···
 	intel_fb_bo_framebuffer_fini(obj);
 err_frontbuffer_put:
 	intel_frontbuffer_put(intel_fb->frontbuffer);
+err_free_panic:
+	kfree(intel_fb->panic);
+
 	return ret;
 }
 
···
 struct intel_framebuffer *intel_framebuffer_alloc(void)
 {
 	struct intel_framebuffer *intel_fb;
-	struct intel_panic *panic;
 
 	intel_fb = kzalloc(sizeof(*intel_fb), GFP_KERNEL);
 	if (!intel_fb)
 		return NULL;
-
-	panic = intel_panic_alloc();
-	if (!panic) {
-		kfree(intel_fb);
-		return NULL;
-	}
-
-	intel_fb->panic = panic;
 
 	return intel_fb;
 }