linux-kernel - [PATCH] drm/efidrm: ensure screen

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Message-Id: <20250411125554.1453825-1-arnd@kernel.org>
Date: Fri, 11 Apr 2025 14:55:47 +0200
From: Arnd Bergmann <arnd@...nel.org>
To: Thomas Zimmermann <tzimmermann@...e.de>,
	Javier Martinez Canillas <javierm@...hat.com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Nathan Chancellor <nathan@...nel.org>
Cc: Arnd Bergmann <arnd@...db.de>,
	Nick Desaulniers <nick.desaulniers+lkml@...il.com>,
	Bill Wendling <morbo@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	llvm@...ts.linux.dev
Subject: [PATCH] drm/efidrm: ensure screen_base is initialized

From: Arnd Bergmann <arnd@...db.de>

clang points out that there is a code path that leads to undefined behavior:

drivers/gpu/drm/sysfb/efidrm.c:353:11: error: variable 'screen_base' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
  353 |         else if (mem_flags & EFI_MEMORY_WB)
      |                  ^~~~~~~~~~~~~~~~~~~~~~~~~

Add the missing initialization.

Fixes: 32ae90c66fb6 ("drm/sysfb: Add efidrm for EFI displays")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/gpu/drm/sysfb/efidrm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/sysfb/efidrm.c b/drivers/gpu/drm/sysfb/efidrm.c
index af90064a4c04..85fc37c1e87a 100644
--- a/drivers/gpu/drm/sysfb/efidrm.c
+++ b/drivers/gpu/drm/sysfb/efidrm.c
@@ -353,6 +353,9 @@ static struct efidrm_device *efidrm_device_create(struct drm_driver *drv,
 	else if (mem_flags & EFI_MEMORY_WB)
 		screen_base = devm_memremap(&pdev->dev, mem->start, resource_size(mem),
 					    MEMREMAP_WB);
+	else
+		screen_base = NULL;
+
 	if (!screen_base)
 		return ERR_PTR(-ENOMEM);
 	iosys_map_set_vaddr_iomem(&sysfb->fb_addr, screen_base);
-- 
2.39.5