fb84efa28a
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] <TASK>
[ 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 <zackr@vmware.com>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Zack Rusin <zackr@vmware.com>
Fixes: 873eb3b118 ("fbdev: Disable sysfb device registration when removing conflicting FBs")
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Zhen Lei <thunder.leizhen@huawei.com>
Cc: Changcheng Deng <deng.changcheng@zte.com.cn>
Link: https://patchwork.freedesktop.org/patch/msgid/20220617121027.30273-1-tzimmermann@suse.de
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.