[PATCH V3] video/aperture: optionally match the device in sysfb_disable()
Thomas Zimmermann
tzimmermann at suse.de
Thu Aug 22 15:10:29 UTC 2024
Am 21.08.24 um 21:11 schrieb Alex Deucher:
> In aperture_remove_conflicting_pci_devices(), we currently only
> call sysfb_disable() on vga class devices. This leads to the
> following problem when the pimary device is not VGA compatible:
>
> 1. A PCI device with a non-VGA class is the boot display
> 2. That device is probed first and it is not a VGA device so
> sysfb_disable() is not called, but the device resources
> are freed by aperture_detach_platform_device()
> 3. Non-primary GPU has a VGA class and it ends up calling sysfb_disable()
> 4. NULL pointer dereference via sysfb_disable() since the resources
> have already been freed by aperture_detach_platform_device() when
> it was called by the other device.
>
> Fix this by passing a device pointer to sysfb_disable() and checking
> the device to determine if we should execute it or not.
>
> v2: Fix build when CONFIG_SCREEN_INFO is not set
> v3: Move device check into the mutex
> Drop primary variable in aperture_remove_conflicting_pci_devices()
> Drop __init on pci sysfb_pci_dev_is_enabled()
>
> Fixes: 5ae3716cfdcd ("video/aperture: Only remove sysfb on the default vga pci device")
> Cc: Javier Martinez Canillas <javierm at redhat.com>
> Cc: Thomas Zimmermann <tzimmermann at suse.de>
> Cc: Helge Deller <deller at gmx.de>
> Cc: Sam Ravnborg <sam at ravnborg.org>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
> Cc: stable at vger.kernel.org
This change also makes aperture_remove_conflicting_pci_devices() much
cleaner. Thanks a lot. Reviewed-by: Thomas Zimmermann <tzimmermann at suse.de>
> ---
> drivers/firmware/sysfb.c | 19 +++++++++++++------
> drivers/of/platform.c | 2 +-
> drivers/video/aperture.c | 11 +++--------
> include/linux/sysfb.h | 4 ++--
> 4 files changed, 19 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/firmware/sysfb.c b/drivers/firmware/sysfb.c
> index 880ffcb50088..ac4680dc463f 100644
> --- a/drivers/firmware/sysfb.c
> +++ b/drivers/firmware/sysfb.c
> @@ -39,6 +39,8 @@ static struct platform_device *pd;
> static DEFINE_MUTEX(disable_lock);
> static bool disabled;
>
> +static struct device *sysfb_parent_dev(const struct screen_info *si);
> +
> static bool sysfb_unregister(void)
> {
> if (IS_ERR_OR_NULL(pd))
> @@ -52,6 +54,7 @@ static bool sysfb_unregister(void)
>
> /**
> * sysfb_disable() - disable the Generic System Framebuffers support
> + * @dev: the device to check if non-NULL
> *
> * This disables the registration of system framebuffer devices that match the
> * generic drivers that make use of the system framebuffer set up by firmware.
> @@ -61,17 +64,21 @@ static bool sysfb_unregister(void)
> * Context: The function can sleep. A @disable_lock mutex is acquired to serialize
> * against sysfb_init(), that registers a system framebuffer device.
> */
> -void sysfb_disable(void)
> +void sysfb_disable(struct device *dev)
> {
> + struct screen_info *si = &screen_info;
> +
> mutex_lock(&disable_lock);
> - sysfb_unregister();
> - disabled = true;
> + if (!dev || dev == sysfb_parent_dev(si)) {
> + sysfb_unregister();
> + disabled = true;
> + }
> mutex_unlock(&disable_lock);
> }
> EXPORT_SYMBOL_GPL(sysfb_disable);
>
> #if defined(CONFIG_PCI)
> -static __init bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev)
> +static bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev)
> {
> /*
> * TODO: Try to integrate this code into the PCI subsystem
> @@ -87,13 +94,13 @@ static __init bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev)
> return true;
> }
> #else
> -static __init bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev)
> +static bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev)
> {
> return false;
> }
> #endif
>
> -static __init struct device *sysfb_parent_dev(const struct screen_info *si)
> +static struct device *sysfb_parent_dev(const struct screen_info *si)
> {
> struct pci_dev *pdev;
>
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 389d4ea6bfc1..ef622d41eb5b 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -592,7 +592,7 @@ static int __init of_platform_default_populate_init(void)
> * This can happen for example on DT systems that do EFI
> * booting and may provide a GOP handle to the EFI stub.
> */
> - sysfb_disable();
> + sysfb_disable(NULL);
> of_platform_device_create(node, NULL, NULL);
> of_node_put(node);
> }
> diff --git a/drivers/video/aperture.c b/drivers/video/aperture.c
> index 561be8feca96..2b5a1e666e9b 100644
> --- a/drivers/video/aperture.c
> +++ b/drivers/video/aperture.c
> @@ -293,7 +293,7 @@ int aperture_remove_conflicting_devices(resource_size_t base, resource_size_t si
> * ask for this, so let's assume that a real driver for the display
> * was already probed and prevent sysfb to register devices later.
> */
> - sysfb_disable();
> + sysfb_disable(NULL);
>
> aperture_detach_devices(base, size);
>
> @@ -346,15 +346,10 @@ EXPORT_SYMBOL(__aperture_remove_legacy_vga_devices);
> */
> int aperture_remove_conflicting_pci_devices(struct pci_dev *pdev, const char *name)
> {
> - bool primary = false;
> resource_size_t base, size;
> int bar, ret = 0;
>
> - if (pdev == vga_default_device())
> - primary = true;
> -
> - if (primary)
> - sysfb_disable();
> + sysfb_disable(&pdev->dev);
>
> for (bar = 0; bar < PCI_STD_NUM_BARS; ++bar) {
> if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
> @@ -370,7 +365,7 @@ int aperture_remove_conflicting_pci_devices(struct pci_dev *pdev, const char *na
> * that consumes the VGA framebuffer I/O range. Remove this
> * device as well.
> */
> - if (primary)
> + if (pdev == vga_default_device())
> ret = __aperture_remove_legacy_vga_devices(pdev);
>
> return ret;
> diff --git a/include/linux/sysfb.h b/include/linux/sysfb.h
> index c9cb657dad08..bef5f06a91de 100644
> --- a/include/linux/sysfb.h
> +++ b/include/linux/sysfb.h
> @@ -58,11 +58,11 @@ struct efifb_dmi_info {
>
> #ifdef CONFIG_SYSFB
>
> -void sysfb_disable(void);
> +void sysfb_disable(struct device *dev);
>
> #else /* CONFIG_SYSFB */
>
> -static inline void sysfb_disable(void)
> +static inline void sysfb_disable(struct device *dev)
> {
> }
>
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
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