linux-kernel - [PATCH v2] drm: Fix the length of event_string in drm_dev_wedged

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Message-Id: <20250408112728.244146-1-jiangfeng@kylinos.cn>
Date: Tue,  8 Apr 2025 19:27:28 +0800
From: jiangfeng@...inos.cn
To: maarten.lankhorst@...ux.intel.com,
	mripard@...nel.org,
	tzimmermann@...e.de,
	airlied@...il.com,
	simona@...ll.ch,
	rodrigo.vivi@...el.com,
	christian.koenig@....com,
	raag.jadav@...el.com,
	andrealmeid@...lia.com
Cc: dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	Feng Jiang <jiangfeng@...inos.cn>
Subject: [PATCH v2] drm: Fix the length of event_string in drm_dev_wedged_event()

From: Feng Jiang <jiangfeng@...inos.cn>

When calling scnprintf() to append recovery method to event_string,
the second argument should be `sizeof(event_string) - len`, otherwise
there is a potential overflow problem.

Fixes: b7cf9f4ac1b8 ("drm: Introduce device wedged event")
Signed-off-by: Feng Jiang <jiangfeng@...inos.cn>
---
v2:
- update commit message
- keep scnprintf() as a single line
---
 drivers/gpu/drm/drm_drv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 17fc5dc708f4..60e5ac179c15 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -549,7 +549,7 @@ int drm_dev_wedged_event(struct drm_device *dev, unsigned long method)
 		if (drm_WARN_ONCE(dev, !recovery, "invalid recovery method %u\n", opt))
 			break;
 
-		len += scnprintf(event_string + len, sizeof(event_string), "%s,", recovery);
+		len += scnprintf(event_string + len, sizeof(event_string) - len, "%s,", recovery);
 	}
 
 	if (recovery)
-- 
2.25.1