| Message ID | 20220107110723.323276-3-javierm@redhat.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | video: A couple of fixes for the vga16fb driver | expand |
Hi Javier, On Fri, Jan 7, 2022 at 9:00 PM Javier Martinez Canillas <javierm@redhat.com> wrote: > The vga16fb framebuffer driver only supports Enhanced Graphics Adapter > (EGA) and Video Graphics Array (VGA) 16 color graphic cards. > > But it doesn't check if the adapter is one of those or if a VGA16 mode > is used. This means that the driver will be probed even if a VESA BIOS > Extensions (VBE) or Graphics Output Protocol (GOP) interface is used. > > This issue has been present for a long time but it was only exposed by > commit d391c5827107 ("drivers/firmware: move x86 Generic System > Framebuffers support") since the platform device registration to match > the {vesa,efi}fb drivers is done later as a consequence of that change. > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=215001 > Fixes: d391c5827107 ("drivers/firmware: move x86 Generic System Framebuffers support") > Reported-by: Kris Karas <bugs-a21@moonlit-rail.com> > Cc: <stable@vger.kernel.org> # 5.15.x > Signed-off-by: Javier Martinez Canillas <javierm@redhat.com> > Tested-by: Kris Karas <bugs-a21@moonlit-rail.com> Thanks for your patch! > --- a/drivers/video/fbdev/vga16fb.c > +++ b/drivers/video/fbdev/vga16fb.c > @@ -1422,6 +1422,18 @@ static int __init vga16fb_init(void) > > vga16fb_setup(option); > #endif > + > + /* only EGA and VGA in 16 color graphic mode are supported */ > + if (screen_info.orig_video_isVGA != VIDEO_TYPE_EGAC && > + screen_info.orig_video_isVGA != VIDEO_TYPE_VGAC) > + return -ENODEV; Probably these checks should be wrapped inside a check for CONFIG_X86? All non-x86 architectures (except for 2 MIPS platforms) treat orig_video_isVGA as a boolean flag, and just assign 1 to it. > + > + if (screen_info.orig_video_mode != 0x0D && /* 320x200/4 (EGA) */ > + screen_info.orig_video_mode != 0x0E && /* 640x200/4 (EGA) */ > + screen_info.orig_video_mode != 0x10 && /* 640x350/4 (EGA) */ > + screen_info.orig_video_mode != 0x12) /* 640x480/4 (VGA) */ > + return -ENODEV; > + Likewise. A long time ago, I used vga16fb on a PPC box to use a standard PC graphics card (initialized using an emulator for the card's BIOS ROM), as a second display. The above changes would break such a use case. > ret = platform_driver_register(&vga16fb_driver); > > if (!ret) { Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
diff --git a/drivers/video/fbdev/vga16fb.c b/drivers/video/fbdev/vga16fb.c index 3347c9b6a332..72b6aeceeff8 100644 --- a/drivers/video/fbdev/vga16fb.c +++ b/drivers/video/fbdev/vga16fb.c @@ -1422,6 +1422,18 @@ static int __init vga16fb_init(void) vga16fb_setup(option); #endif + + /* only EGA and VGA in 16 color graphic mode are supported */ + if (screen_info.orig_video_isVGA != VIDEO_TYPE_EGAC && + screen_info.orig_video_isVGA != VIDEO_TYPE_VGAC) + return -ENODEV; + + if (screen_info.orig_video_mode != 0x0D && /* 320x200/4 (EGA) */ + screen_info.orig_video_mode != 0x0E && /* 640x200/4 (EGA) */ + screen_info.orig_video_mode != 0x10 && /* 640x350/4 (EGA) */ + screen_info.orig_video_mode != 0x12) /* 640x480/4 (VGA) */ + return -ENODEV; + ret = platform_driver_register(&vga16fb_driver); if (!ret) {
The vga16fb framebuffer driver only supports Enhanced Graphics Adapter (EGA) and Video Graphics Array (VGA) 16 color graphic cards. But it doesn't check if the adapter is one of those or if a VGA16 mode is used. This means that the driver will be probed even if a VESA BIOS Extensions (VBE) or Graphics Output Protocol (GOP) interface is used. This issue has been present for a long time but it was only exposed by commit d391c5827107 ("drivers/firmware: move x86 Generic System Framebuffers support") since the platform device registration to match the {vesa,efi}fb drivers is done later as a consequence of that change. Link: https://bugzilla.kernel.org/show_bug.cgi?id=215001 Fixes: d391c5827107 ("drivers/firmware: move x86 Generic System Framebuffers support") Reported-by: Kris Karas <bugs-a21@moonlit-rail.com> Cc: <stable@vger.kernel.org> # 5.15.x Signed-off-by: Javier Martinez Canillas <javierm@redhat.com> Tested-by: Kris Karas <bugs-a21@moonlit-rail.com> --- drivers/video/fbdev/vga16fb.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)