[v2,2/2] media: atomisp: Fix me->stages error checking in sh_css_sp_init_pipeline()

The current error-checking of me->stages in sh_css_sp_init_pipeline()
has some issues / weirdness:

1. It is checked at the top of the function, but only using the atomisp
   custom assert() macro which e.g. smatch does not recognize

2. It is first dereferenced in "first_binary = me->stages->binary", but
   outside of the assert it is checked much later, triggering the following
   smatch warning:

drivers/staging/media/atomisp/pci/sh_css_sp.c:1255 sh_css_sp_init_pipeline()
warn: variable dereferenced before check 'me->stages' (see line 1224)

Drop the custom assert() calls (note 'me' is never NULL) and instead add
a regular check for me->stages not being set.

Reported-by: Hans Verkuil <hverkuil@xs4all.nl>
Closes: https://lore.kernel.org/linux-media/7c8fc5b4-280e-844e-cdf5-b6ec2a1616aa@xs4all.nl/
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/staging/media/atomisp/pci/sh_css_sp.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

Hi Hans,

On Sun, Jul 30, 2023 at 11:33 PM Hans de Goede <hdegoede@redhat.com> wrote:
>
> The current error-checking of me->stages in sh_css_sp_init_pipeline()
> has some issues / weirdness:
>
> 1. It is checked at the top of the function, but only using the atomisp
>    custom assert() macro which e.g. smatch does not recognize
>
> 2. It is first dereferenced in "first_binary = me->stages->binary", but
>    outside of the assert it is checked much later, triggering the following
>    smatch warning:
>
> drivers/staging/media/atomisp/pci/sh_css_sp.c:1255 sh_css_sp_init_pipeline()
> warn: variable dereferenced before check 'me->stages' (see line 1224)
>
> Drop the custom assert() calls (note 'me' is never NULL) and instead add
> a regular check for me->stages not being set.
>
> Reported-by: Hans Verkuil <hverkuil@xs4all.nl>
> Closes: https://lore.kernel.org/linux-media/7c8fc5b4-280e-844e-cdf5-b6ec2a1616aa@xs4all.nl/
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
>  drivers/staging/media/atomisp/pci/sh_css_sp.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/staging/media/atomisp/pci/sh_css_sp.c b/drivers/staging/media/atomisp/pci/sh_css_sp.c
> index 4ef1c9e61ea8..eba70d4800a1 100644
> --- a/drivers/staging/media/atomisp/pci/sh_css_sp.c
> +++ b/drivers/staging/media/atomisp/pci/sh_css_sp.c
> @@ -51,6 +51,7 @@
>  #include "ia_css_event.h"
>  #include "mmu_device.h"
>  #include "ia_css_spctrl.h"
> +#include "atomisp_internal.h"
>
>  #ifndef offsetof
>  #define offsetof(T, x) ((unsigned int)&(((T *)0)->x))
> @@ -1210,14 +1211,15 @@ sh_css_sp_init_pipeline(struct ia_css_pipeline *me,
>         struct ia_css_binary         *first_binary = NULL;
>         struct ia_css_pipe *pipe = NULL;
>         unsigned int num;
> -
>         enum ia_css_pipe_id pipe_id = id;
>         unsigned int thread_id;
>         u8 if_config_index, tmp_if_config_index;
>
> -       assert(me);
> -
> -       assert(me->stages);
> +       if (!me->stages) {
> +               dev_err(atomisp_dev, "%s called on a pipeline without stages\n",
> +                       __func__);
> +               return; /* FIXME should be able to return an error */

Agree, an error handling is needed for the caller.

> +       }
>
>         first_binary = me->stages->binary;
>
> @@ -1250,8 +1252,8 @@ sh_css_sp_init_pipeline(struct ia_css_pipeline *me,
>         } /* if (first_binary != NULL) */
>
>         /* Signal the host immediately after start for SP_ISYS_COPY only */
> -       if ((me->num_stages == 1) && me->stages &&
> -           (me->stages->sp_func == IA_CSS_PIPELINE_ISYS_COPY))
> +       if (me->num_stages == 1 &&
> +           me->stages->sp_func == IA_CSS_PIPELINE_ISYS_COPY)
>                 sh_css_sp_group.config.no_isp_sync = true;
>
>         /* Init stage data */
> --
> 2.41.0
>

It is good for me.

Reviewed-by: Kate Hsuan <hpa@redhat.com>



--
BR,
Kate