On Sun, 2023-01-29 at 16:17 +0100, Samuel Thibault wrote: > blit_x and blit_y are u32, so fbcon currently cannot support fonts > larger than 32x32. > > The 32x32 case also needs shifting an unsigned int, to properly set > bit > 31, otherwise we get "UBSAN: shift-out-of-bounds in fbcon_set_font", > as reported on: > > http://lore.kernel.org/all/IA1PR07MB98308653E259A6F2CE94A4AFABCE9@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx > Kernel Branch: 6.2.0-rc5-next-20230124 > Kernel config: > https://drive.google.com/file/d/1F-LszDAizEEH0ZX0HcSR06v5q8FPl2Uv/view?usp=sharing > Reproducer: > https://drive.google.com/file/d/1mP1jcLBY7vWCNM60OMf-ogw-urQRjNrm/view?usp=sharing > > Reported-by: Sanan Hasanov <sanan.hasanov@xxxxxxxxxxxxxxx> > Signed-off-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx> > Fixes: 2d2699d98492 ("fbcon: font setting should check limitation of > driver") > Cc: stable@xxxxxxxxxxxxxxx > > --- > v1 -> v2: > - Use BIT macro instead of fixing bit test by hand. > - Add Fixes and Cc: stable headers. > > Index: linux-6.0/drivers/video/fbdev/core/fbcon.c > =================================================================== > --- linux-6.0.orig/drivers/video/fbdev/core/fbcon.c > +++ linux-6.0/drivers/video/fbdev/core/fbcon.c > @@ -2489,9 +2489,12 @@ static int fbcon_set_font(struct vc_data > h > FBCON_SWAP(info->var.rotate, info->var.yres, info- > >var.xres)) > return -EINVAL; > > + if (font->width > 32 || font->height > 32) > + return -EINVAL; > + > /* Make sure drawing engine can handle the font */ > - if (!(info->pixmap.blit_x & (1 << (font->width - 1))) || > - !(info->pixmap.blit_y & (1 << (font->height - 1)))) > + if (!(info->pixmap.blit_x & BIT(font->width - 1)) || > + !(info->pixmap.blit_y & BIT(font->height - 1))) > return -EINVAL; > > /* Make sure driver can handle the font length */ Tested-by: Miko Larsson <mikoxyzzz@xxxxxxxxx> -- ~miko
