Removing the bochs PCI device should mark the DRM device as unplugged without removing it. Hence clear the respective call to drm_dev_put() from bochs_pci_remove(). Fixes a double unref in devm_drm_dev_init_release(). An example error message is shown below: [ 32.958338] BUG: KASAN: use-after-free in drm_dev_put.part.0+0x1b/0x90 [ 32.958850] Write of size 4 at addr ffff888152134004 by task (udev-worker)/591 [ 32.959574] CPU: 3 UID: 0 PID: 591 Comm: (udev-worker) Tainted: G E 6.13.0-rc2-1-default+ #3417 [ 32.960316] Tainted: [E]=UNSIGNED_MODULE [ 32.960637] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-2-gc13ff2cd-prebuilt.qemu.org 04/01/2014 [ 32.961429] Call Trace: [ 32.961433] <TASK> [ 32.961439] dump_stack_lvl+0x68/0x90 [ 32.961452] print_address_description.constprop.0+0x88/0x330 [ 32.961461] ? preempt_count_sub+0x14/0xc0 [ 32.961473] print_report+0xe2/0x1d0 [ 32.961479] ? srso_alias_return_thunk+0x5/0xfbef5 [ 32.963725] ? __virt_addr_valid+0x143/0x320 [ 32.964077] ? srso_alias_return_thunk+0x5/0xfbef5 [ 32.964463] ? drm_dev_put.part.0+0x1b/0x90 [ 32.964817] kasan_report+0xce/0x1a0 [ 32.965123] ? drm_dev_put.part.0+0x1b/0x90 [ 32.965474] kasan_check_range+0xff/0x1c0 [ 32.965806] drm_dev_put.part.0+0x1b/0x90 [ 32.966138] release_nodes+0x84/0xc0 [ 32.966447] devres_release_all+0xd2/0x110 [ 32.966788] ? __pfx_devres_release_all+0x10/0x10 [ 32.967177] ? preempt_count_sub+0x14/0xc0 [ 32.967523] device_unbind_cleanup+0x16/0xc0 [ 32.967886] really_probe+0x1b7/0x570 [ 32.968207] __driver_probe_device+0xca/0x1b0 [ 32.968568] driver_probe_device+0x4a/0xf0 [ 32.968907] __driver_attach+0x10b/0x290 [ 32.969239] ? __pfx___driver_attach+0x10/0x10 [ 32.969598] bus_for_each_dev+0xc0/0x110 [ 32.969923] ? __pfx_bus_for_each_dev+0x10/0x10 [ 32.970291] ? bus_add_driver+0x17a/0x2b0 [ 32.970622] ? srso_alias_return_thunk+0x5/0xfbef5 [ 32.971011] bus_add_driver+0x19a/0x2b0 [ 32.971335] driver_register+0xd8/0x160 [ 32.971671] ? __pfx_bochs_pci_driver_init+0x10/0x10 [bochs] [ 32.972130] do_one_initcall+0xba/0x390 [...] After unplugging the DRM device, clients will close their references. Closing the final reference will also release the DRM device. Reported-by: Dr. David Alan Gilbert <dave@xxxxxxxxxxx> Closes: https://lore.kernel.org/lkml/Z18dbfDAiFadsSdg@gallifrey/ Fixes: 04826f588682 ("drm/bochs: Allocate DRM device in struct bochs_device") Cc: Thomas Zimmermann <tzimmermann@xxxxxxx> Cc: Gerd Hoffmann <kraxel@xxxxxxxxxx> Cc: virtualization@xxxxxxxxxxxxxxx Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx> --- drivers/gpu/drm/tiny/bochs.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/gpu/drm/tiny/bochs.c b/drivers/gpu/drm/tiny/bochs.c index 89a699370a59..c67e1f906785 100644 --- a/drivers/gpu/drm/tiny/bochs.c +++ b/drivers/gpu/drm/tiny/bochs.c @@ -757,7 +757,6 @@ static void bochs_pci_remove(struct pci_dev *pdev) drm_dev_unplug(dev); drm_atomic_helper_shutdown(dev); - drm_dev_put(dev); } static void bochs_pci_shutdown(struct pci_dev *pdev) -- 2.47.1
