dapm_kcontrol_data is freed as part of dapm_kcontrol_free(), leaving the paths list pointer dangling in the list.

This leads to system crash when we try to unload and reload sound card. I hit this bug during ADSP crash/reboot test case on Dragon board DB410c.

Below is the kernel BUG with SLAB Poisoning

============================================================================= BUG kmalloc-128 (Tainted: G W ): Poison overwritten -----------------------------------------------------------------------------

Disabling lock debugging due to kernel taint INFO: 0xffff80003cf1c310-0xffff80003cf1c31f. First byte 0x10 instead of 0x6b INFO: Allocated in dapm_kcontrol_data_alloc.isra.37+0x34/0x2a8 age=6929 cpu=0 pid=50 __slab_alloc.isra.24+0x24/0x38 kmem_cache_alloc+0x190/0x1d8 dapm_kcontrol_data_alloc.isra.37+0x34/0x2a8 dapm_create_or_share_kcontrol+0x1d4/0x290 snd_soc_dapm_new_widgets+0x410/0x568 snd_soc_register_card+0xa58/0xcd0 apq8016_sbc_bind+0x31c/0x458 try_to_bring_up_master+0x204/0x2e8 component_add+0x94/0x178 q6pcm_routing_probe+0x38/0x48 platform_drv_probe+0x58/0xb8 driver_probe_device+0x324/0x478 __device_attach_driver+0xa8/0x160 bus_for_each_drv+0x48/0x98 __device_attach+0xc0/0x158 device_initial_probe+0x10/0x18 INFO: Freed in dapm_kcontrol_free+0x40/0x50 age=3135 cpu=1 pid=1792 kfree+0x1bc/0x1d0 dapm_kcontrol_free+0x40/0x50 snd_ctl_free_one+0x20/0x38 snd_ctl_remove+0xf0/0x108 snd_ctl_dev_free+0x3c/0x70 __snd_device_free+0x50/0x88 snd_device_free_all+0x2c/0x50 release_card_device+0x1c/0x78 device_release+0x34/0x98 kobject_put+0x90/0x1f0 put_device+0x14/0x20 snd_card_free+0x54/0x70 snd_soc_unregister_card+0x84/0x138 snd_soc_unregister_component+0xa4/0xd0 q6routing_dai_unbind+0x44/0x78 component_unbind.isra.4+0x28/0x50 INFO: Slab 0xffff7e0000f3c700 objects=25 used=0 fp=0xffff80003cf1fc80 flags=0xfffc00000008100 INFO: Object 0x (ptrval) @offset=768 fp=0x (ptrval)

Redzone (ptrval): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................ Redzone (ptrval): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................ Redzone (ptrval): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................ Redzone (ptrval): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................ Redzone (ptrval): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................ Redzone (ptrval): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................ Redzone (ptrval): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................ Redzone (ptrval): bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................ Object (ptrval): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk Object (ptrval): 10 c3 f1 3c 00 80 ff ff 10 c3 f1 3c 00 80 ff ff ...<.......<.... Object (ptrval): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk Object (ptrval): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk Object (ptrval): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk Object (ptrval): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk Object (ptrval): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk Object (ptrval): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 kkkkkkkkkkkkkkk. Redzone (ptrval): bb bb bb bb bb bb bb bb ........ Padding (ptrval): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZZZZZZZZZ Padding (ptrval): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZZZZZZZZZ Padding (ptrval): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZZZZZZZZZ Padding (ptrval): 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZZZZZZZZZ CPU: 1 PID: 1792 Comm: sh Tainted: G B W 4.17.0-rc7-02229-gb429ee402d16-dirty #202 Hardware name: Qualcomm Technologies, Inc. APQ 8016 SBC (DT) Call trace: dump_backtrace+0x0/0x1b0 show_stack+0x14/0x20 dump_stack+0x9c/0xbc print_trailer+0x124/0x1d8 check_bytes_and_report+0xe8/0x120 check_object+0x24c/0x288 __free_slab+0x9c/0x2f0 discard_slab+0x60/0x88 __slab_free+0x35c/0x3e8 kfree+0x1bc/0x1d0 snd_soc_dapm_free_widget+0xac/0xd0 snd_soc_dapm_free+0x64/0xb8 soc_remove_component+0x50/0x80 soc_remove_dai_links+0x110/0x208 snd_soc_unregister_card+0x9c/0x138 snd_soc_unregister_component+0xa4/0xd0 q6routing_dai_unbind+0x44/0x78 component_unbind.isra.4+0x28/0x50 component_unbind_all+0xc0/0xe8 apq8016_sbc_unbind+0x50/0xa0 take_down_master+0x24/0x48 component_del+0x90/0x130 q6afe_dai_dev_remove+0x40/0x68 platform_drv_remove+0x24/0x50 device_release_driver_internal+0x170/0x208 device_release_driver+0x14/0x20 bus_remove_device+0xcc/0x150 device_del+0x10c/0x310 platform_device_del.part.3+0x24/0x90 platform_device_unregister+0x18/0x30 of_platform_device_destroy+0x94/0x98 q6afe_remove+0x20/0x38 apr_device_remove+0x30/0x70 device_release_driver_internal+0x170/0x208 device_release_driver+0x14/0x20 bus_remove_device+0xcc/0x150 device_del+0x10c/0x310 device_unregister+0x1c/0x70 apr_remove_device+0xc/0x18 device_for_each_child+0x50/0x80 apr_remove+0x18/0x20 rpmsg_dev_remove+0x38/0x68 device_release_driver_internal+0x170/0x208 device_release_driver+0x14/0x20 bus_remove_device+0xcc/0x150 device_del+0x10c/0x310 device_unregister+0x1c/0x70 qcom_smd_remove_device+0xc/0x18 device_for_each_child+0x50/0x80 qcom_smd_unregister_edge+0x3c/0x70 smd_subdev_remove+0x18/0x28 rproc_stop+0x48/0xd8 rproc_shutdown+0x60/0xe8 state_store+0xbc/0xf8 dev_attr_store+0x18/0x28 sysfs_kf_write+0x3c/0x50 kernfs_fop_write+0x118/0x1e0 __vfs_write+0x18/0x110 vfs_write+0xa4/0x1a8 ksys_write+0x48/0xb0 sys_write+0xc/0x18 el0_svc_naked+0x30/0x34

Signed-off-by: Srinivas Kandagatla srinivas.kandagatla@linaro.org --- sound/soc/soc-dapm.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c index 1e9a36389667..36a39ba30226 100644 --- a/sound/soc/soc-dapm.c +++ b/sound/soc/soc-dapm.c @@ -433,6 +433,8 @@ static int dapm_kcontrol_data_alloc(struct snd_soc_dapm_widget *widget, static void dapm_kcontrol_free(struct snd_kcontrol *kctl) { struct dapm_kcontrol_data *data = snd_kcontrol_chip(kctl); + + list_del(&data->paths); kfree(data->wlist); kfree(data); }