[PATCH] fbmem: don't allow too huge resolutions
Tetsuo Handa
penguin-kernel at i-love.sakura.ne.jp
Tue Aug 31 15:23:58 UTC 2021
On 2021/08/31 15:48, Geert Uytterhoeven wrote:
> Furthermore, this restricts the virtual frame buffer size on 64-bit,
> too, while graphics cards can have much more than 4 GiB of RAM.
Excuse me, but do you mean that some hardware allows allocating more than
UINT_MAX bytes of memory for kernel frame buffer drivers?
> IMHO that should be fixed in vga16fb, too.
According to https://elixir.bootlin.com/linux/v5.14/A/ident/fb_check_var ,
there are 89 files. Randomly picking up drivers/video/fbdev/udlfb.c as
an example. dlfb_is_valid_mode() from dlfb_ops_check_var() is doing
if (mode->xres * mode->yres > dlfb->sku_pixel_limit)
return 0;
return 1;
where max dlfb->sku_pixel_limit seems to be 2048 * 1152 but I think we need
same overflow check. I want to avoid patching individual modules if possible.
That depends on whether some hardware needs to allocate more than UINT_MAX
bytes of memory.
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