linux-kernel - [PATCH v2] drm/i915: Fix format string truncation warning

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Message-ID: <20251205113500.684286-2-ardb@kernel.org>
Date: Fri,  5 Dec 2025 12:35:01 +0100
From: Ard Biesheuvel <ardb@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: Ard Biesheuvel <ardb@...nel.org>,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@...el.com>,
	Tvrtko Ursulin <tursulin@...ulin.net>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	intel-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH v2] drm/i915: Fix format string truncation warning

GCC notices that the 16-byte uabi_name field could theoretically be too
small for the formatted string if the instance number exceeds 100.

So grow the field to 20 bytes.

drivers/gpu/drm/i915/intel_memory_region.c: In function ‘intel_memory_region_create’:
drivers/gpu/drm/i915/intel_memory_region.c:273:61: error: ‘%u’ directive output may be truncated writing between 1 and 5 bytes into a region of size between 3 and 11 [-Werror=format-truncation=]
  273 |         snprintf(mem->uabi_name, sizeof(mem->uabi_name), "%s%u",
      |                                                             ^~
drivers/gpu/drm/i915/intel_memory_region.c:273:58: note: directive argument in the range [0, 65535]
  273 |         snprintf(mem->uabi_name, sizeof(mem->uabi_name), "%s%u",
      |                                                          ^~~~~~
drivers/gpu/drm/i915/intel_memory_region.c:273:9: note: ‘snprintf’ output between 7 and 19 bytes into a destination of size 16
  273 |         snprintf(mem->uabi_name, sizeof(mem->uabi_name), "%s%u",
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  274 |                  intel_memory_type_str(type), instance);
      |                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
v2: grow buffer instead of changing the output

Cc: Jani Nikula <jani.nikula@...ux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@...el.com>
Cc: Tvrtko Ursulin <tursulin@...ulin.net>
Cc: David Airlie <airlied@...il.com>
Cc: Simona Vetter <simona@...ll.ch>
Cc: intel-gfx@...ts.freedesktop.org
Cc: dri-devel@...ts.freedesktop.org

 drivers/gpu/drm/i915/intel_memory_region.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_memory_region.h b/drivers/gpu/drm/i915/intel_memory_region.h
index b3b75be9ced5..e9a4e6090fe0 100644
--- a/drivers/gpu/drm/i915/intel_memory_region.h
+++ b/drivers/gpu/drm/i915/intel_memory_region.h
@@ -72,7 +72,7 @@ struct intel_memory_region {
 	u16 instance;
 	enum intel_region_id id;
 	char name[16];
-	char uabi_name[16];
+	char uabi_name[20];
 	bool private; /* not for userspace */
 
 	struct {
-- 
2.47.3