[alsa-devel] Kernel crash at snd_ctl_find_numid+0x38/0x6c in kernel 4.4

[Clemens Ladisch]

Rohit Kumar wrote:
> I am getting NULL pointer dereference occasionally at snd_ctl_find_numid+0x38/0x6c in 4.4 kernel while accessing snd_kcontrol. The issue is reproduced ocassionally. Can anybody provide any pointer in fixing the issue. Below is the stack trace :
>
>   2662.430298:   <2> PC is at snd_ctl_find_numid+0x38/0x6c
>   2662.437819:   <2> LR is at snd_ctl_find_id+0x38/0xd8
>   2662.662838:   <2> [<ffffff8008c4e35c>] snd_ctl_find_numid+0x38/0x6c
>   2662.667513:   <2> [<ffffff8008c4e900>] snd_ctl_find_id+0x38/0xd8
>   2662.673415:   <2> [<ffffff8008c4f488>] snd_ctl_elem_info+0x40/0x11c
>   2662.678799:   <2> [<ffffff8008c4df5c>] snd_ctl_ioctl_compat+0x3f4/0x740
>   2662.684644:   <2> [<ffffff800823477c>] compat_SyS_ioctl+0x124/0xd88
>
> There is no specific usecase when the issue is observed. Sometimes issue occurs during bootup and sometimes during audio usecase.

Which hardware?  Which driver?  Does it occur with the latest kernel?


Regards,
Clemens