diff options
| author | Javier Martinez Canillas <javierm@redhat.com> | 2021-11-11 12:57:57 +0100 |
|---|---|---|
| committer | Javier Martinez Canillas <javierm@redhat.com> | 2021-11-17 10:15:05 +0100 |
| commit | fb561bf9abde49f7e00fdbf9ed2ccf2d86cac8ee (patch) | |
| tree | 1c5cf23c0590bc95cf5b43aca47c1509849a8d52 | |
| parent | 963d0b3569354230f6e2c36a286ef270a8901878 (diff) | |
fbdev: Prevent probing generic drivers if a FB is already registereddrm-misc-fixes-2021-11-18
The efifb and simplefb drivers just render to a pre-allocated frame buffer
and rely on the display hardware being initialized before the kernel boots.
But if another driver already probed correctly and registered a fbdev, the
generic drivers shouldn't be probed since an actual driver for the display
hardware is already present.
This is more likely to occur after commit d391c5827107 ("drivers/firmware:
move x86 Generic System Framebuffers support") since the "efi-framebuffer"
and "simple-framebuffer" platform devices are registered at a later time.
Link: https://lore.kernel.org/r/20211110200253.rfudkt3edbd3nsyj@lahvuun/
Fixes: d391c5827107 ("drivers/firmware: move x86 Generic System Framebuffers support")
Reported-by: Ilya Trukhanov <lahvuun@gmail.com>
Cc: <stable@vger.kernel.org> # 5.15.x
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Tested-by: Ilya Trukhanov <lahvuun@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211111115757.1351045-1-javierm@redhat.com
| -rw-r--r-- | drivers/video/fbdev/efifb.c | 11 | ||||
| -rw-r--r-- | drivers/video/fbdev/simplefb.c | 11 |
2 files changed, 22 insertions, 0 deletions
diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c index edca3703b964..ea42ba6445b2 100644 --- a/drivers/video/fbdev/efifb.c +++ b/drivers/video/fbdev/efifb.c @@ -351,6 +351,17 @@ static int efifb_probe(struct platform_device *dev) char *option = NULL; efi_memory_desc_t md; + /* + * Generic drivers must not be registered if a framebuffer exists. + * If a native driver was probed, the display hardware was already + * taken and attempting to use the system framebuffer is dangerous. + */ + if (num_registered_fb > 0) { + dev_err(&dev->dev, + "efifb: a framebuffer is already registered\n"); + return -EINVAL; + } + if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI || pci_dev_disabled) return -ENODEV; diff --git a/drivers/video/fbdev/simplefb.c b/drivers/video/fbdev/simplefb.c index 62f0ded70681..b63074fd892e 100644 --- a/drivers/video/fbdev/simplefb.c +++ b/drivers/video/fbdev/simplefb.c @@ -407,6 +407,17 @@ static int simplefb_probe(struct platform_device *pdev) struct simplefb_par *par; struct resource *mem; + /* + * Generic drivers must not be registered if a framebuffer exists. + * If a native driver was probed, the display hardware was already + * taken and attempting to use the system framebuffer is dangerous. + */ + if (num_registered_fb > 0) { + dev_err(&pdev->dev, + "simplefb: a framebuffer is already registered\n"); + return -EINVAL; + } + if (fb_get_options("simplefb", NULL)) return -ENODEV; |