Re: [PATCH 1/1] fbdev: atyfb: Fix buffer overflow

[Jani Nikula]

On Thu, 27 Mar 2025, Denis Arefev <arefev@xxxxxxxxx> wrote:
> The value LCD_MISC_CNTL is used in the 'aty_st_lcd()' function to
> calculate an index for accessing an array element of size 9.
> This may cause a buffer overflow.

The fix is to fix it, not silently brush it under the carpet.

BR,
Jani.

>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Denis Arefev <arefev@xxxxxxxxx>
> ---
>  drivers/video/fbdev/aty/atyfb_base.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/video/fbdev/aty/atyfb_base.c b/drivers/video/fbdev/aty/atyfb_base.c
> index 210fd3ac18a4..93eb5eb6042b 100644
> --- a/drivers/video/fbdev/aty/atyfb_base.c
> +++ b/drivers/video/fbdev/aty/atyfb_base.c
> @@ -149,6 +149,8 @@ static const u32 lt_lcd_regs[] = {
>  void aty_st_lcd(int index, u32 val, const struct atyfb_par *par)
>  {
>  	if (M64_HAS(LT_LCD_REGS)) {
> +		if ((u32)index >= ARRAY_SIZE(lt_lcd_regs))
> +			return;
>  		aty_st_le32(lt_lcd_regs[index], val, par);
>  	} else {
>  		unsigned long temp;
> @@ -164,6 +166,8 @@ void aty_st_lcd(int index, u32 val, const struct atyfb_par *par)
>  u32 aty_ld_lcd(int index, const struct atyfb_par *par)
>  {
>  	if (M64_HAS(LT_LCD_REGS)) {
> +		if ((u32)index >= ARRAY_SIZE(lt_lcd_regs))
> +			return 0;
>  		return aty_ld_le32(lt_lcd_regs[index], par);
>  	} else {
>  		unsigned long temp;

-- 
Jani Nikula, Intel