From 84499c5d220a4f8fb0a35fa4673148525c81ea83 Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Fri, 17 Jun 2022 14:10:27 +0200 Subject: drm/aperture: Run fbdev removal before internal helpers Always run fbdev removal first to remove simpledrm via sysfb_disable(). This clears the internal state. The later call to drm_aperture_detach_drivers() then does nothing. Otherwise, with drm_aperture_detach_drivers() running first, the call to sysfb_disable() uses inconsistent state. Example backtrace show below: BUG: KASAN: use-after-free in device_del+0x79/0x5f0 Read of size 8 at addr ffff888108185050 by task systemd-udevd/311 CPU: 0 PID: 311 Comm: systemd-udevd Tainted: G E 5.19.0-rc2-1-default+ #1689 Hardware name: HP ProLiant DL120 G7, BIOS J01 04/21/2011 Call Trace: device_del+0x79/0x5f0 platform_device_del.part.0+0x19/0xe0 platform_device_unregister+0x1c/0x30 sysfb_disable+0x2d/0x70 remove_conflicting_framebuffers+0x1c/0xf0 remove_conflicting_pci_framebuffers+0x130/0x1a0 drm_aperture_remove_conflicting_pci_framebuffers+0x86/0xb0 mgag200_pci_probe+0x2d/0x140 [mgag200] Signed-off-by: Thomas Zimmermann Fixes: 873eb3b11860 ("fbdev: Disable sysfb device registration when removing conflicting FBs") Cc: Javier Martinez Canillas Cc: Daniel Vetter Cc: Daniel Vetter Cc: Sam Ravnborg Cc: Helge Deller Cc: Thomas Zimmermann Cc: Alex Deucher Cc: Zhen Lei Cc: Changcheng Deng Reviewed-by: Zack Rusin Reviewed-by: Javier Martinez Canillas Signed-off-by: Linus Torvalds --- drivers/gpu/drm/drm_aperture.c | 26 +++++++++++++++----------- 1 file changed, 15 insertions(+), 11 deletions(-) (limited to 'drivers') diff --git a/drivers/gpu/drm/drm_aperture.c b/drivers/gpu/drm/drm_aperture.c index 74bd4a76b253..059fd71424f6 100644 --- a/drivers/gpu/drm/drm_aperture.c +++ b/drivers/gpu/drm/drm_aperture.c @@ -329,7 +329,20 @@ int drm_aperture_remove_conflicting_pci_framebuffers(struct pci_dev *pdev, const struct drm_driver *req_driver) { resource_size_t base, size; - int bar, ret = 0; + int bar, ret; + + /* + * WARNING: Apparently we must kick fbdev drivers before vgacon, + * otherwise the vga fbdev driver falls over. + */ +#if IS_REACHABLE(CONFIG_FB) + ret = remove_conflicting_pci_framebuffers(pdev, req_driver->name); + if (ret) + return ret; +#endif + ret = vga_remove_vgacon(pdev); + if (ret) + return ret; for (bar = 0; bar < PCI_STD_NUM_BARS; ++bar) { if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM)) @@ -339,15 +352,6 @@ int drm_aperture_remove_conflicting_pci_framebuffers(struct pci_dev *pdev, drm_aperture_detach_drivers(base, size); } - /* - * WARNING: Apparently we must kick fbdev drivers before vgacon, - * otherwise the vga fbdev driver falls over. - */ -#if IS_REACHABLE(CONFIG_FB) - ret = remove_conflicting_pci_framebuffers(pdev, req_driver->name); -#endif - if (ret == 0) - ret = vga_remove_vgacon(pdev); - return ret; + return 0; } EXPORT_SYMBOL(drm_aperture_remove_conflicting_pci_framebuffers); -- cgit v1.2.3-59-g8ed1b