From c6f48e59ece0123f6a11527ad4d89b21c2d65b87 Mon Sep 17 00:00:00 2001 From: Shixiong Ou Date: Tue, 25 Aug 2026 18:41:34 +0800 Subject: [PATCH] drm/sysfb: ofdrm: Fix integer overflow in fb_size calculation The framebuffer size calculation `fb_size = linebytes * height` can overflow when both values are large (e.g., 46341 * 46341 > INT_MAX). Since linebytes and height are both int types, the multiplication is performed as int * int, which results in undefined behavior on overflow. Use check_mul_overflow() to detect and prevent this overflow, consistent with the approach used in simpledrm.c and corebootdrm.c. Signed-off-by: Shixiong Ou Reviewed-by: Thomas Zimmermann Signed-off-by: Thomas Zimmermann Fixes: c8a17756c425 ("drm/ofdrm: Add ofdrm for Open Firmware framebuffers") Cc: # v6.2+ Link: https://patch.msgid.link/20260825104134.669676-1-oushixiong1025@163.com --- drivers/gpu/drm/sysfb/ofdrm.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/sysfb/ofdrm.c b/drivers/gpu/drm/sysfb/ofdrm.c index 819aed466727..a6dc34b9ec0f 100644 --- a/drivers/gpu/drm/sysfb/ofdrm.c +++ b/drivers/gpu/drm/sysfb/ofdrm.c @@ -2,6 +2,7 @@ #include #include +#include #include #include #include @@ -913,7 +914,10 @@ static struct ofdrm_device *ofdrm_device_create(struct drm_driver *drv, return ERR_PTR(-EINVAL); } - fb_size = linebytes * height; + if (check_mul_overflow(linebytes, height, &fb_size)) { + drm_err(dev, "framebuffer size exceeds maximum\n"); + return ERR_PTR(-EINVAL); + } /* * Try to figure out the address of the framebuffer. Unfortunately, Open