From: Adrián Larumbe adrian.larumbe@collabora.com
[ Upstream commit 31c519981eb141c7ec39bfd5be25d35f02edb868 ]
Unloading the driver triggers the following KASAN warning:
[ +0.006275] ============================================================= [ +0.000029] BUG: KASAN: use-after-free in __list_del_entry_valid+0xe0/0x1a0 [ +0.000026] Read of size 8 at addr ffff000020c395e0 by task rmmod/2695
[ +0.000019] CPU: 5 PID: 2695 Comm: rmmod Tainted: G C O 5.19.0-rc6-lrmbkasan+ #1 [ +0.000013] Hardware name: Hardkernel ODROID-N2Plus (DT) [ +0.000008] Call trace: [ +0.000007] dump_backtrace+0x1ec/0x280 [ +0.000013] show_stack+0x24/0x80 [ +0.000008] dump_stack_lvl+0x98/0xd4 [ +0.000011] print_address_description.constprop.0+0x80/0x520 [ +0.000011] print_report+0x128/0x260 [ +0.000007] kasan_report+0xb8/0xfc [ +0.000008] __asan_report_load8_noabort+0x3c/0x50 [ +0.000010] __list_del_entry_valid+0xe0/0x1a0 [ +0.000009] drm_atomic_private_obj_fini+0x30/0x200 [drm] [ +0.000172] drm_bridge_detach+0x94/0x260 [drm] [ +0.000145] drm_encoder_cleanup+0xa4/0x290 [drm] [ +0.000144] drm_mode_config_cleanup+0x118/0x740 [drm] [ +0.000143] drm_mode_config_init_release+0x1c/0x2c [drm] [ +0.000144] drm_managed_release+0x170/0x414 [drm] [ +0.000142] drm_dev_put.part.0+0xc0/0x124 [drm] [ +0.000143] drm_dev_put+0x20/0x30 [drm] [ +0.000142] meson_drv_unbind+0x1d8/0x2ac [meson_drm] [ +0.000028] take_down_aggregate_device+0xb0/0x160 [ +0.000016] component_del+0x18c/0x360 [ +0.000009] meson_dw_hdmi_remove+0x28/0x40 [meson_dw_hdmi] [ +0.000015] platform_remove+0x64/0xb0 [ +0.000009] device_remove+0xb8/0x154 [ +0.000009] device_release_driver_internal+0x398/0x5b0 [ +0.000009] driver_detach+0xac/0x1b0 [ +0.000009] bus_remove_driver+0x158/0x29c [ +0.000009] driver_unregister+0x70/0xb0 [ +0.000008] platform_driver_unregister+0x20/0x2c [ +0.000008] meson_dw_hdmi_platform_driver_exit+0x1c/0x30 [meson_dw_hdmi] [ +0.000012] __do_sys_delete_module+0x288/0x400 [ +0.000011] __arm64_sys_delete_module+0x5c/0x80 [ +0.000009] invoke_syscall+0x74/0x260 [ +0.000009] el0_svc_common.constprop.0+0xcc/0x260 [ +0.000009] do_el0_svc+0x50/0x70 [ +0.000007] el0_svc+0x68/0x1a0 [ +0.000012] el0t_64_sync_handler+0x11c/0x150 [ +0.000008] el0t_64_sync+0x18c/0x190
[ +0.000018] Allocated by task 0: [ +0.000007] (stack is not available)
[ +0.000011] Freed by task 2695: [ +0.000008] kasan_save_stack+0x2c/0x5c [ +0.000011] kasan_set_track+0x2c/0x40 [ +0.000008] kasan_set_free_info+0x28/0x50 [ +0.000009] ____kasan_slab_free+0x128/0x1d4 [ +0.000008] __kasan_slab_free+0x18/0x24 [ +0.000007] slab_free_freelist_hook+0x108/0x230 [ +0.000011] kfree+0x110/0x35c [ +0.000008] release_nodes+0xf0/0x16c [ +0.000009] devres_release_group+0x180/0x270 [ +0.000008] component_unbind+0x128/0x1e0 [ +0.000010] component_unbind_all+0x1b8/0x264 [ +0.000009] meson_drv_unbind+0x1a0/0x2ac [meson_drm] [ +0.000025] take_down_aggregate_device+0xb0/0x160 [ +0.000009] component_del+0x18c/0x360 [ +0.000009] meson_dw_hdmi_remove+0x28/0x40 [meson_dw_hdmi] [ +0.000012] platform_remove+0x64/0xb0 [ +0.000008] device_remove+0xb8/0x154 [ +0.000009] device_release_driver_internal+0x398/0x5b0 [ +0.000009] driver_detach+0xac/0x1b0 [ +0.000009] bus_remove_driver+0x158/0x29c [ +0.000008] driver_unregister+0x70/0xb0 [ +0.000008] platform_driver_unregister+0x20/0x2c [ +0.000008] meson_dw_hdmi_platform_driver_exit+0x1c/0x30 [meson_dw_hdmi] [ +0.000011] __do_sys_delete_module+0x288/0x400 [ +0.000010] __arm64_sys_delete_module+0x5c/0x80 [ +0.000008] invoke_syscall+0x74/0x260 [ +0.000008] el0_svc_common.constprop.0+0xcc/0x260 [ +0.000008] do_el0_svc+0x50/0x70 [ +0.000007] el0_svc+0x68/0x1a0 [ +0.000009] el0t_64_sync_handler+0x11c/0x150 [ +0.000009] el0t_64_sync+0x18c/0x190
[ +0.000014] The buggy address belongs to the object at ffff000020c39000 which belongs to the cache kmalloc-4k of size 4096 [ +0.000008] The buggy address is located 1504 bytes inside of 4096-byte region [ffff000020c39000, ffff000020c3a000)
[ +0.000016] The buggy address belongs to the physical page: [ +0.000009] page:fffffc0000830e00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x20c38 [ +0.000013] head:fffffc0000830e00 order:3 compound_mapcount:0 compound_pincount:0 [ +0.000008] flags: 0xffff00000010200(slab|head|node=0|zone=0|lastcpupid=0xffff) [ +0.000019] raw: 0ffff00000010200 fffffc0000fd4808 fffffc0000126208 ffff000000002e80 [ +0.000009] raw: 0000000000000000 0000000000020002 00000001ffffffff 0000000000000000 [ +0.000008] page dumped because: kasan: bad access detected
[ +0.000011] Memory state around the buggy address: [ +0.000008] ffff000020c39480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ +0.000007] ffff000020c39500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ +0.000007] >ffff000020c39580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ +0.000007] ^ [ +0.000007] ffff000020c39600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ +0.000007] ffff000020c39680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ +0.000006] ==================================================================
The reason this is happening is unloading meson-dw-hdmi will cause the component API to take down the aggregate device, which in turn will cause all devres-managed memory to be freed, including the struct dw_hdmi allocated in dw_hdmi_probe. This struct embeds a struct drm_bridge that is added at the end of the function, and which is later on picked up in meson_encoder_hdmi_init.
However, when attaching the bridge to the encoder created in meson_encoder_hdmi_init, it's linked to the encoder's bridge chain, from where it never leaves, even after devres_release_group is called when the driver's components are unbound and the embedding structure freed.
Then, when calling drm_dev_put in the aggregate driver's unbind function, drm_bridge_detach is called for every single bridge linked to the encoder, including the one whose memory had already been deallocated.
Fix by calling component_unbind_all after drm_dev_put.
Signed-off-by: Adrián Larumbe adrian.larumbe@collabora.com Reviewed-by: Neil Armstrong neil.armstrong@linaro.org Signed-off-by: Neil Armstrong neil.armstrong@linaro.org Link: https://patchwork.freedesktop.org/patch/msgid/20220919010940.419893-2-adrian... Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/meson/meson_drv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/meson/meson_drv.c b/drivers/gpu/drm/meson/meson_drv.c index a56607501d36..56c7daeb116a 100644 --- a/drivers/gpu/drm/meson/meson_drv.c +++ b/drivers/gpu/drm/meson/meson_drv.c @@ -387,9 +387,9 @@ static void meson_drv_unbind(struct device *dev) drm_dev_unregister(drm); drm_kms_helper_poll_fini(drm); drm_atomic_helper_shutdown(drm); - component_unbind_all(dev, drm); free_irq(priv->vsync_irq, drm); drm_dev_put(drm); + component_unbind_all(dev, drm);
if (priv->afbcd.ops) priv->afbcd.ops->exit(priv);