On 6/30/22 21:00, Geert Uytterhoeven wrote: > Hi Helge, > > On Wed, Jun 29, 2022 at 10:00 PM Helge Deller <deller@xxxxxx> wrote: >> The virtual screen size can't be smaller than the physical screen size. >> Based on the general rule that we round up user-provided input if >> neccessary, adjust the virtual screen size as well if needed. >> >> Signed-off-by: Helge Deller <deller@xxxxxx> >> Cc: stable@xxxxxxxxxxxxxxx # v5.4+ > > Thanks for your patch! > >> --- a/drivers/video/fbdev/core/fbmem.c >> +++ b/drivers/video/fbdev/core/fbmem.c >> @@ -1106,6 +1106,11 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, >> return -EFAULT; >> console_lock(); >> lock_fb_info(info); >> + /* adjust virtual screen size if user missed it */ >> + if (var.xres_virtual < var.xres) >> + var.xres_virtual = var.xres; >> + if (var.yres_virtual < var.yres) >> + var.yres_virtual = var.yres; >> ret = fb_set_var(info, &var); >> if (!ret) >> fbcon_update_vcs(info, var.activate & FB_ACTIVATE_ALL); > > Given "[PATCH 4/5] fbmem: Prevent invalid virtual screen sizes in > fb_set_var", I don't think we need this patch. We do. > Moreover, this > patch will prevent triggering the WARN_ON()s in [PATCH 4/5] Right. > in the most common buggy case of drivers plainly ignoring var.[xy]res_virtual. In summary: This patch #2 is fixing up user-space invalid input and is not allowed to trigger any WARN_ON(). We could drop patch #4, but then we wouldn't catch bad drivers. Helge
