From: Greg Kroah-Hartman gregkh@linuxfoundation.org

From: Tong Zhang ztong0001@gmail.com

commit 874a52f9b693ed8bf7a92b3592a547ce8a684e6f upstream.

drm_fbdev_cleanup() can be called when fb_helper->buffer is null, hence fb_helper->buffer should be checked before calling drm_client_buffer_vunmap(). This buffer is also checked in drm_client_framebuffer_delete(), so we should also do the same thing for drm_client_buffer_vunmap().

[ 199.128742] RIP: 0010:drm_client_buffer_vunmap+0xd/0x20 [ 199.129031] Code: 43 18 48 8b 53 20 49 89 45 00 49 89 55 08 5b 44 89 e0 41 5c 41 5d 41 5e 5d c3 0f 1f 00 53 48 89 fb 48 8d 7f 10 e8 73 7d a1 ff <48> 8b 7b 10 48 8d 73 18 5b e9 75 53 fc ff 0 f 1f 44 00 00 48 b8 00 [ 199.130041] RSP: 0018:ffff888103f3fc88 EFLAGS: 00010282 [ 199.130329] RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff8214d46d [ 199.130733] RDX: 1ffffffff079c6b9 RSI: 0000000000000246 RDI: ffffffff83ce35c8 [ 199.131119] RBP: ffff888103d25458 R08: 0000000000000001 R09: fffffbfff0791761 [ 199.131505] R10: ffffffff83c8bb07 R11: fffffbfff0791760 R12: 0000000000000000 [ 199.131891] R13: ffff888103d25468 R14: ffff888103d25418 R15: ffff888103f18120 [ 199.132277] FS: 00007f36fdcbb6a0(0000) GS:ffff88815b400000(0000) knlGS:0000000000000000 [ 199.132721] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 199.133033] CR2: 0000000000000010 CR3: 0000000103d26000 CR4: 00000000000006f0 [ 199.133420] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 199.133807] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 199.134195] Call Trace: [ 199.134333] drm_fbdev_cleanup+0x179/0x1a0 [ 199.134562] drm_fbdev_client_unregister+0x2b/0x40 [ 199.134828] drm_client_dev_unregister+0xa8/0x180 [ 199.135088] drm_dev_unregister+0x61/0x110 [ 199.135315] mgag200_pci_remove+0x38/0x52 [mgag200] [ 199.135586] pci_device_remove+0x62/0xe0 [ 199.135806] device_release_driver_internal+0x148/0x270 [ 199.136094] driver_detach+0x76/0xe0 [ 199.136294] bus_remove_driver+0x7e/0x100 [ 199.136521] pci_unregister_driver+0x28/0xf0 [ 199.136759] __x64_sys_delete_module+0x268/0x300 [ 199.137016] ? __ia32_sys_delete_module+0x300/0x300 [ 199.137285] ? call_rcu+0x3e4/0x580 [ 199.137481] ? fpregs_assert_state_consistent+0x4d/0x60 [ 199.137767] ? exit_to_user_mode_prepare+0x2f/0x130 [ 199.138037] do_syscall_64+0x33/0x40 [ 199.138237] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 199.138517] RIP: 0033:0x7f36fdc3dcf7

Signed-off-by: Tong Zhang ztong0001@gmail.com Fixes: 763aea17bf57 ("drm/fb-helper: Unmap client buffer during shutdown") Cc: Thomas Zimmermann tzimmermann@suse.de Cc: Sam Ravnborg sam@ravnborg.org Cc: Maxime Ripard mripard@kernel.org Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: David Airlie airlied@linux.ie Cc: Daniel Vetter daniel@ffwll.ch Cc: dri-devel@lists.freedesktop.org Cc: stable@vger.kernel.org # v5.11+ Signed-off-by: Thomas Zimmermann tzimmermann@suse.de Link: https://patchwork.freedesktop.org/patch/msgid/20210228044625.171151-1-ztong0... Signed-off-by: Maarten Lankhorst maarten.lankhorst@linux.intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/drm_fb_helper.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -2043,7 +2043,7 @@ static void drm_fbdev_cleanup(struct drm

if (shadow) vfree(shadow); - else + else if (fb_helper->buffer) drm_client_buffer_vunmap(fb_helper->buffer);

drm_client_framebuffer_delete(fb_helper->buffer);