On Tue, Sep 30, 2025 at 09:12:21PM +0200, Helge Deller wrote: > On 9/15/25 08:36, Janne Grunau wrote: > > The pm_domain cleanup can not be devres managed as it uses struct > > simplefb_par which is allocated within struct fb_info by > > framebuffer_alloc(). This allocation is explicitly freed by > > unregister_framebuffer() in simplefb_remove(). > > Devres managed cleanup runs after the device remove call and thus can no > > longer access struct simplefb_par. > > Call simplefb_detach_genpds() explicitly from simplefb_destroy() like > > the cleanup functions for clocks and regulators. > > > > Fixes an use after free on M2 Mac mini during > > aperture_remove_conflicting_devices() using the downstream asahi kernel > > with Debian's kernel config. For unknown reasons this started to > > consistently dereference an invalid pointer in v6.16.3 based kernels. > > > > [ 6.736134] BUG: KASAN: slab-use-after-free in > > simplefb_detach_genpds+0x58/0x220 > > [ 6.743545] Read of size 4 at addr ffff8000304743f0 by task > > (udev-worker)/227 > > [ 6.750697] > > [ 6.752182] CPU: 6 UID: 0 PID: 227 Comm: (udev-worker) Tainted: G S > > 6.16.3-asahi+ #16 PREEMPTLAZY > > [ 6.752186] Tainted: [S]=CPU_OUT_OF_SPEC > > [ 6.752187] Hardware name: Apple Mac mini (M2, 2023) (DT) > > [ 6.752189] Call trace: > > [ 6.752190] show_stack+0x34/0x98 (C) > > [ 6.752194] dump_stack_lvl+0x60/0x80 > > [ 6.752197] print_report+0x17c/0x4d8 > > [ 6.752201] kasan_report+0xb4/0x100 > > [ 6.752206] __asan_report_load4_noabort+0x20/0x30 > > [ 6.752209] simplefb_detach_genpds+0x58/0x220 > > [ 6.752213] devm_action_release+0x50/0x98 > > [ 6.752216] release_nodes+0xd0/0x2c8 > > [ 6.752219] devres_release_all+0xfc/0x178 > > [ 6.752221] device_unbind_cleanup+0x28/0x168 > > [ 6.752224] device_release_driver_internal+0x34c/0x470 > > [ 6.752228] device_release_driver+0x20/0x38 > > [ 6.752231] bus_remove_device+0x1b0/0x380 > > [ 6.752234] device_del+0x314/0x820 > > [ 6.752238] platform_device_del+0x3c/0x1e8 > > [ 6.752242] platform_device_unregister+0x20/0x50 > > [ 6.752246] aperture_detach_platform_device+0x1c/0x30 > > [ 6.752250] aperture_detach_devices+0x16c/0x290 > > [ 6.752253] aperture_remove_conflicting_devices+0x34/0x50 > > ... > > [ 6.752343] > > [ 6.967409] Allocated by task 62: > > [ 6.970724] kasan_save_stack+0x3c/0x70 > > [ 6.974560] kasan_save_track+0x20/0x40 > > [ 6.978397] kasan_save_alloc_info+0x40/0x58 > > [ 6.982670] __kasan_kmalloc+0xd4/0xd8 > > [ 6.986420] __kmalloc_noprof+0x194/0x540 > > [ 6.990432] framebuffer_alloc+0xc8/0x130 > > [ 6.994444] simplefb_probe+0x258/0x2378 > > ... > > [ 7.054356] > > [ 7.055838] Freed by task 227: > > [ 7.058891] kasan_save_stack+0x3c/0x70 > > [ 7.062727] kasan_save_track+0x20/0x40 > > [ 7.066565] kasan_save_free_info+0x4c/0x80 > > [ 7.070751] __kasan_slab_free+0x6c/0xa0 > > [ 7.074675] kfree+0x10c/0x380 > > [ 7.077727] framebuffer_release+0x5c/0x90 > > [ 7.081826] simplefb_destroy+0x1b4/0x2c0 > > [ 7.085837] put_fb_info+0x98/0x100 > > [ 7.089326] unregister_framebuffer+0x178/0x320 > > [ 7.093861] simplefb_remove+0x3c/0x60 > > [ 7.097611] platform_remove+0x60/0x98 > > [ 7.101361] device_remove+0xb8/0x160 > > [ 7.105024] device_release_driver_internal+0x2fc/0x470 > > [ 7.110256] device_release_driver+0x20/0x38 > > [ 7.114529] bus_remove_device+0x1b0/0x380 > > [ 7.118628] device_del+0x314/0x820 > > [ 7.122116] platform_device_del+0x3c/0x1e8 > > [ 7.126302] platform_device_unregister+0x20/0x50 > > [ 7.131012] aperture_detach_platform_device+0x1c/0x30 > > [ 7.136157] aperture_detach_devices+0x16c/0x290 > > [ 7.140779] aperture_remove_conflicting_devices+0x34/0x50 > > ... > > > > Reported-by: Daniel Huhardeaux <[email protected]> > > Cc: [email protected] > > Fixes: 92a511a568e44 ("fbdev/simplefb: Add support for generic > > power-domains") > > Signed-off-by: Janne Grunau <[email protected]> > > --- > > Changes in v3: > > - release power-domains on probe errors > > - set par->num_genpds when it's <= 1 > > - set par->num_genpds to 0 after detaching > > - Link to v2: > > https://lore.kernel.org/r/[email protected] > > > > Changes in v2: > > - reworked change due to missed use of `par->num_genpds` before setting > > it. Missed in testing due to mixing up FB_SIMPLE and SYSFB_SIMPLEFB. > > - Link to v1: > > https://lore.kernel.org/r/[email protected] > > --- > > drivers/video/fbdev/simplefb.c | 31 +++++++++++++++++++++++-------- > > 1 file changed, 23 insertions(+), 8 deletions(-) > > applied to fbdev git tree.
Thanks. > > PS: Janne, if you want to push yourself via drm-misc, just let me know and I > drop it... I won't. My request for commit access is still pending. I should fine someone at xdc to ask about that. Janne
