summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorJavier Martinez Canillas <javierm@redhat.com>2021-11-11 12:57:57 +0100
committerJavier Martinez Canillas <javierm@redhat.com>2021-11-17 10:15:05 +0100
commitfb561bf9abde49f7e00fdbf9ed2ccf2d86cac8ee (patch)
tree1c5cf23c0590bc95cf5b43aca47c1509849a8d52
parent963d0b3569354230f6e2c36a286ef270a8901878 (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.c11
-rw-r--r--drivers/video/fbdev/simplefb.c11
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;