2023-03-15 07:19:07

by Wei Chen

Subject: [PATCH] fbdev: nvidia: Fix potential divide by zero

variable var->pixclock can be set by user. In case it
equals to zero, divide by zero would occur in nvidiafb_set_par.

Similar crashes have happened in other fbdev drivers. There
is no check and modification on var->pixclock along the call
chain to nvidia_check_var and nvidiafb_set_par. We believe it
could also be triggered in driver nvidia from user site.

Signed-off-by: Wei Chen <[email protected]>
---
drivers/video/fbdev/nvidia/nvidia.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/video/fbdev/nvidia/nvidia.c b/drivers/video/fbdev/nvidia/nvidia.c
index e60a276b4855..ea4ba3dfb96b 100644
--- a/drivers/video/fbdev/nvidia/nvidia.c
+++ b/drivers/video/fbdev/nvidia/nvidia.c
@@ -764,6 +764,8 @@ static int nvidiafb_check_var(struct fb_var_screeninfo *var,
int pitch, err = 0;

NVTRACE_ENTER();
+ if (!var->pixclock)
+ return -EINVAL;

var->transp.offset = 0;
var->transp.length = 0;
--
2.25.1

2023-03-16 13:34:59

by Helge Deller

Subject: Re: [PATCH] fbdev: nvidia: Fix potential divide by zero

On 3/15/23 08:18, Wei Chen wrote:
> variable var->pixclock can be set by user. In case it
> equals to zero, divide by zero would occur in nvidiafb_set_par.
>
> Similar crashes have happened in other fbdev drivers. There
> is no check and modification on var->pixclock along the call
> chain to nvidia_check_var and nvidiafb_set_par. We believe it
> could also be triggered in driver nvidia from user site.
>
> Signed-off-by: Wei Chen <[email protected]>

applied all four patches.

Thanks!
Helge

> ---
> drivers/video/fbdev/nvidia/nvidia.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/video/fbdev/nvidia/nvidia.c b/drivers/video/fbdev/nvidia/nvidia.c
> index e60a276b4855..ea4ba3dfb96b 100644
> --- a/drivers/video/fbdev/nvidia/nvidia.c
> +++ b/drivers/video/fbdev/nvidia/nvidia.c
> @@ -764,6 +764,8 @@ static int nvidiafb_check_var(struct fb_var_screeninfo *var,
> int pitch, err = 0;
>
> NVTRACE_ENTER();
> + if (!var->pixclock)
> + return -EINVAL;
>
> var->transp.offset = 0;
> var->transp.length = 0;