* [PATCH] drm/sysfb: ofdrm: Fix integer overflow in fb_size calculation
@ 2026-07-24 9:41 oushixiong1025
2026-07-24 11:37 ` Thomas Zimmermann
0 siblings, 1 reply; 4+ messages in thread
From: oushixiong1025 @ 2026-07-24 9:41 UTC (permalink / raw)
To: Thomas Zimmermann
Cc: Javier Martinez Canillas, Maarten Lankhorst, Maxime Ripard,
David Airlie, Simona Vetter, dri-devel, linux-kernel,
Shixiong Ou
From: Shixiong Ou <oushixiong@kylinos.cn>
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 <oushixiong@kylinos.cn>
---
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 <linux/aperture.h>
#include <linux/of_address.h>
+#include <linux/overflow.h>
#include <linux/pci.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
@@ -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
--
2.25.1
No virus found
Checked by Hillstone Network AntiVirus
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] drm/sysfb: ofdrm: Fix integer overflow in fb_size calculation
2026-07-24 9:41 [PATCH] drm/sysfb: ofdrm: Fix integer overflow in fb_size calculation oushixiong1025
@ 2026-07-24 11:37 ` Thomas Zimmermann
0 siblings, 0 replies; 4+ messages in thread
From: Thomas Zimmermann @ 2026-07-24 11:37 UTC (permalink / raw)
To: oushixiong1025
Cc: Javier Martinez Canillas, Maarten Lankhorst, Maxime Ripard,
David Airlie, Simona Vetter, dri-devel, linux-kernel,
Shixiong Ou
Am 24.07.26 um 11:41 schrieb oushixiong1025@163.com:
> From: Shixiong Ou <oushixiong@kylinos.cn>
>
> 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 <oushixiong@kylinos.cn>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Thanks for the fix.
> ---
> 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 <linux/aperture.h>
> #include <linux/of_address.h>
> +#include <linux/overflow.h>
> #include <linux/pci.h>
> #include <linux/platform_device.h>
> #include <linux/pm.h>
> @@ -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
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, (HRB 36809, AG Nürnberg)
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] drm/sysfb: ofdrm: Fix integer overflow in fb_size calculation
@ 2026-08-25 10:41 oushixiong1025
2026-08-26 6:59 ` Thomas Zimmermann
0 siblings, 1 reply; 4+ messages in thread
From: oushixiong1025 @ 2026-08-25 10:41 UTC (permalink / raw)
To: Thomas Zimmermann
Cc: Javier Martinez Canillas, Maarten Lankhorst, Maxime Ripard,
David Airlie, Simona Vetter, dri-devel, linux-kernel,
Shixiong Ou
From: Shixiong Ou <oushixiong@kylinos.cn>
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 <oushixiong@kylinos.cn>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
---
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 <linux/aperture.h>
#include <linux/of_address.h>
+#include <linux/overflow.h>
#include <linux/pci.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
@@ -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
--
2.25.1
No virus found
Checked by Hillstone Network AntiVirus
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] drm/sysfb: ofdrm: Fix integer overflow in fb_size calculation
2026-08-25 10:41 oushixiong1025
@ 2026-08-26 6:59 ` Thomas Zimmermann
0 siblings, 0 replies; 4+ messages in thread
From: Thomas Zimmermann @ 2026-08-26 6:59 UTC (permalink / raw)
To: oushixiong1025
Cc: Javier Martinez Canillas, Maarten Lankhorst, Maxime Ripard,
David Airlie, Simona Vetter, dri-devel, linux-kernel,
Shixiong Ou
Merged into drm-misc-fixes
Am 25.08.26 um 12:41 schrieb oushixiong1025@163.com:
> From: Shixiong Ou <oushixiong@kylinos.cn>
>
> 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 <oushixiong@kylinos.cn>
> Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
> 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 <linux/aperture.h>
> #include <linux/of_address.h>
> +#include <linux/overflow.h>
> #include <linux/pci.h>
> #include <linux/platform_device.h>
> #include <linux/pm.h>
> @@ -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
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, (HRB 36809, AG Nürnberg)
^ permalink raw reply [flat|nested] 4+ messages in thread
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2026-07-24 9:41 [PATCH] drm/sysfb: ofdrm: Fix integer overflow in fb_size calculation oushixiong1025
2026-07-24 11:37 ` Thomas Zimmermann
2026-08-25 10:41 oushixiong1025
2026-08-26 6:59 ` Thomas Zimmermann
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