[alsa-devel] [alsa-lib][PATCH] ctl: add dimension validator

[Takashi Iwai]

On Thu, 07 Jul 2016 16:22:08 +0200,
Takashi Sakamoto wrote:
> 
> Linux 4.7 or former have no validator of dimension information. This can
> causes an issue related to user-defined element set. For example, When
> calculated total members in multi-dimensional matrix is larger than actual
> capacity of snd_ctl_elem_value_t, processes to handle the element can
> cause buffer-over-run.
> 
> For backward portability of this userspace library, this commit adds a
> validator of dimension information. When userspace applications give
> invalid dimension information to APIs to add element set, they receive
> -EINVAL.
> 
> Signed-off-by: Takashi Sakamoto <o-takashi at sakamocchi.jp>
> ---
>  src/control/control.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
> 
> diff --git a/src/control/control.c b/src/control/control.c
> index 2ad3e0d..ee6b1d8 100644
> --- a/src/control/control.c
> +++ b/src/control/control.c
> @@ -91,6 +91,7 @@ I/O operations.
>  #include <fcntl.h>
>  #include <signal.h>
>  #include <sys/poll.h>
> +#include <stdbool.h>
>  #include "control_local.h"
>  
>  /**
> @@ -302,6 +303,32 @@ int snd_ctl_elem_info(snd_ctl_t *ctl, snd_ctl_elem_info_t *info)
>  	return ctl->ops->element_info(ctl, info);
>  }
>  
> +static bool validate_element_member_dimension(struct snd_ctl_elem_info *info)

In alsa-lib user-space, we use snd_ctl_elem_info_t.  Please stick with
it.  In theory, this type can be different from the kernel ABI.


thanks,

Takashi