From: Thomas Zimmermann Date: Fri, 17 Jun 2022 12:10:27 +0000 (+0200) Subject: drm/aperture: Run fbdev removal before internal helpers X-Git-Tag: v6.1~6^2^2~99 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=bf43e4521ff3223a613f3a496991a22a4d78e04b;p=platform%2Fkernel%2Flinux-starfive.git 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: [ 11.663422] ================================================================== [ 11.663426] BUG: KASAN: use-after-free in device_del+0x79/0x5f0 [ 11.663435] Read of size 8 at addr ffff888108185050 by task systemd-udevd/311 [ 11.663440] CPU: 0 PID: 311 Comm: systemd-udevd Tainted: G E 5 .19.0-rc2-1-default+ #1689 [ 11.663445] Hardware name: HP ProLiant DL120 G7, BIOS J01 04/21/2011 [ 11.663447] Call Trace: [ 11.663449] [ 11.663451] ? device_del+0x79/0x5f0 [ 11.663456] dump_stack_lvl+0x5b/0x73 [ 11.663462] print_address_description.constprop.0+0x1f/0x1b0 [ 11.663468] ? device_del+0x79/0x5f0 [ 11.663471] ? device_del+0x79/0x5f0 [ 11.663475] print_report.cold+0x3c/0x21c [ 11.663481] ? lock_acquired+0x87/0x1e0 [ 11.663484] ? lock_acquired+0x87/0x1e0 [ 11.663489] ? device_del+0x79/0x5f0 [ 11.663492] kasan_report+0xbf/0xf0 [ 11.663498] ? device_del+0x79/0x5f0 [ 11.663503] device_del+0x79/0x5f0 [ 11.663509] ? device_remove_attrs+0x170/0x170 [ 11.663514] ? lock_is_held_type+0xe8/0x140 [ 11.663523] platform_device_del.part.0+0x19/0xe0 [ 11.663530] platform_device_unregister+0x1c/0x30 [ 11.663535] sysfb_disable+0x2d/0x70 [ 11.663540] remove_conflicting_framebuffers+0x1c/0xf0 [ 11.663546] remove_conflicting_pci_framebuffers+0x130/0x1a0 [ 11.663554] drm_aperture_remove_conflicting_pci_framebuffers+0x86/0xb0 [ 11.663561] ? mgag200_pci_remove+0x30/0x30 [mgag200] [ 11.663578] mgag200_pci_probe+0x2d/0x140 [mgag200] Reported-by: Zack Rusin Signed-off-by: Thomas Zimmermann Reviewed-by: Javier Martinez Canillas Reviewed-by: Zack Rusin Fixes: ee7a69aa38d8 ("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 Link: https://patchwork.freedesktop.org/patch/msgid/20220617121027.30273-1-tzimmermann@suse.de (cherry picked from commit fb84efa28a48e30b87fa1122e8aab8016c7347cd) Signed-off-by: Thomas Zimmermann --- diff --git a/drivers/gpu/drm/drm_aperture.c b/drivers/gpu/drm/drm_aperture.c index 74bd4a7..059fd71 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);