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drm/sysfb: Avoid possible truncation with calculating visible size

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Calculating the visible size of the system framebuffer can result in
truncation of the result. The calculation uses 32-bit arithmetics,
which can overflow if the values for height and stride are large. Fix
the issue by multiplying with mul_u32_u32().

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: 32ae90c66f ("drm/sysfb: Add efidrm for EFI displays")
Fixes: a84eb6abe2 ("drm/sysfb: Add vesadrm for VESA displays")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://lore.kernel.org/dri-devel/20260617114027.1F2A71F000E9@smtp.kernel.org/
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v6.16+
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patch.msgid.link/20260618084327.46567-3-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann 2026-06-18 10:41:58 +02:00
parent 134844856c
commit b771974988
1 changed files with 2 additions and 1 deletions
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3
drivers/gpu/drm/sysfb/drm_sysfb_screen_info.c
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@ -2,6 +2,7 @@
#include <linux/export.h>
#include <linux/limits.h>
#include <linux/math64.h>
#include <linux/minmax.h>
#include <linux/screen_info.h>
@ -67,7 +68,7 @@ EXPORT_SYMBOL(drm_sysfb_get_stride_si);
u64 drm_sysfb_get_visible_size_si(struct drm_device *dev, const struct screen_info *si,
unsigned int height, unsigned int stride, u64 size)
{
u64 vsize = height * stride;
u64 vsize = mul_u32_u32(height, stride);
return drm_sysfb_get_validated_size0(dev, "visible size", vsize, size);
}