Re: [PATCH 5/9] staging: media: atomisp: fix stack overflow in init_pipe_defaults()

[Nathan Chancellor]

On Fri, May 29, 2020 at 10:00:27PM +0200, Arnd Bergmann wrote:
> When building with clang, multiple copies of the structures to be
> initialized are passed around on the stack and copied locally, using an
> insane amount of stack space:
> 
> drivers/staging/media/atomisp/pci/sh_css.c:2371:1: error: stack frame size of 
> 26864 bytes in function 'create_pipe' [-Werror,-Wframe-larger-than=]
> 
> Use constantly-allocated variables plus an explicit memcpy()
> to avoid that.
> 
> Fixes: 6dc9a2568f84 ("media: atomisp: convert default struct values to use 
> compound-literals with designated initializers")
> Signed-off-by: Arnd Bergmann 

Reviewed-by: Nathan Chancellor 

> ---
>  drivers/staging/media/atomisp/pci/sh_css.c | 16 +++-
>  1 file changed, 11 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/staging/media/atomisp/pci/sh_css.c 
> b/drivers/staging/media/atomisp/pci/sh_css.c
> index e91c6029c651..1e8b9d637116 100644
> --- a/drivers/staging/media/atomisp/pci/sh_css.c
> +++ b/drivers/staging/media/atomisp/pci/sh_css.c
> @@ -2264,6 +2264,12 @@ static enum ia_css_err
>  init_pipe_defaults(enum ia_css_pipe_mode mode,
>  struct ia_css_pipe *pipe,
>  bool copy_pipe) {
> + static const struct ia_css_pipe default_pipe = IA_CSS_DEFAULT_PIPE;
> + static const struct ia_css_preview_settings preview = 
> IA_CSS_DEFAULT_PREVIEW_SETTINGS;
> + static const struct ia_css_capture_settings capture = 
> IA_CSS_DEFAULT_CAPTURE_SETTINGS;
> + static const struct ia_css_video_settings video = 
> IA_CSS_DEFAULT_VIDEO_SETTINGS;
> + static const struct ia_css_yuvpp_settings yuvpp = 
> IA_CSS_DEFAULT_YUVPP_SETTINGS;
> +
>   if (!pipe)
>   {
>   IA_CSS_ERROR("NULL pipe parameter");
> @@ -2271,14 +2277,14 @@ init_pipe_defaults(enum ia_css_pipe_mode mode,
>   }
>  
>   /* Initialize pipe to pre-defined defaults */
> - *pipe = IA_CSS_DEFAULT_PIPE;
> + memcpy(pipe, _pipe, sizeof(default_pipe));
>  
>   /* TODO: JB should not be needed, but temporary backward reference */
>   switch (mode)
>   {
>   case IA_CSS_PIPE_MODE_PREVIEW:
>   pipe->mode = IA_CSS_PIPE_ID_PREVIEW;
> - pipe->pipe_settings.preview = IA_CSS_DEFAULT_PREVIEW_SETTINGS;
> + memcpy(>pipe_settings.preview, , sizeof(preview));
>   break;
>   case IA_CSS_PIPE_MODE_CAPTURE:
>   if (copy_pipe) {
> @@ -2286,11 +2292,11 @@ init_pipe_defaults(enum ia_css_pipe_mode mode,
>   } else {
>   pipe->mode = IA_CSS_PIPE_ID_CAPTURE;
>   }
> - pipe->pipe_settings.capture = IA_CSS_DEFAULT_CAPTURE_SETTINGS;
> + memcpy(>pipe_settings.capture, , sizeof(capture));
>   break;
>   case IA_CSS_PIPE_MODE_VIDEO:
>   pipe->mode = IA_CSS_PIPE_ID_VIDEO;
> - pipe->pipe_settings.video = IA_CSS_DEFAULT_VIDEO_SETTINGS;
> + memcpy(>pipe_settings.video, , sizeof(video));
>   break;
>   case IA_CSS_PIPE_MODE_ACC:
>   pipe->mode = IA_CSS_PIPE_ID_ACC;
> @@ -2300,7 +2306,7 @@ init_pipe_defaults(enum ia_css_pipe_mode mode,
>   break;
>   case IA_CSS_PIPE_MODE_YUVPP:
>   pipe->mode = IA_CSS_PIPE_ID_YUVPP;
> - pipe->pipe_settings.yuvpp = IA_CSS_DEFAULT_YUVPP_SETTINGS;
> + memcpy(>pipe_settings.yuvpp, , sizeof(yuvpp));
>   break;
>   default:
>   return IA_CSS_ERR_INVALID_ARGUMENTS;
> -- 
> 2.26.2
> 

[PATCH 5/9] staging: media: atomisp: fix stack overflow in init_pipe_defaults()

[Arnd Bergmann]

When building with clang, multiple copies of the structures to be
initialized are passed around on the stack and copied locally, using an
insane amount of stack space:

drivers/staging/media/atomisp/pci/sh_css.c:2371:1: error: stack frame size of 
26864 bytes in function 'create_pipe' [-Werror,-Wframe-larger-than=]

Use constantly-allocated variables plus an explicit memcpy()
to avoid that.

Fixes: 6dc9a2568f84 ("media: atomisp: convert default struct values to use 
compound-literals with designated initializers")
Signed-off-by: Arnd Bergmann 
---
 drivers/staging/media/atomisp/pci/sh_css.c | 16 +++-
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/media/atomisp/pci/sh_css.c 
b/drivers/staging/media/atomisp/pci/sh_css.c
index e91c6029c651..1e8b9d637116 100644
--- a/drivers/staging/media/atomisp/pci/sh_css.c
+++ b/drivers/staging/media/atomisp/pci/sh_css.c
@@ -2264,6 +2264,12 @@ static enum ia_css_err
 init_pipe_defaults(enum ia_css_pipe_mode mode,
   struct ia_css_pipe *pipe,
   bool copy_pipe) {
+   static const struct ia_css_pipe default_pipe = IA_CSS_DEFAULT_PIPE;
+   static const struct ia_css_preview_settings preview = 
IA_CSS_DEFAULT_PREVIEW_SETTINGS;
+   static const struct ia_css_capture_settings capture = 
IA_CSS_DEFAULT_CAPTURE_SETTINGS;
+   static const struct ia_css_video_settings video = 
IA_CSS_DEFAULT_VIDEO_SETTINGS;
+   static const struct ia_css_yuvpp_settings yuvpp = 
IA_CSS_DEFAULT_YUVPP_SETTINGS;
+
if (!pipe)
{
IA_CSS_ERROR("NULL pipe parameter");
@@ -2271,14 +2277,14 @@ init_pipe_defaults(enum ia_css_pipe_mode mode,
}
 
/* Initialize pipe to pre-defined defaults */
-   *pipe = IA_CSS_DEFAULT_PIPE;
+   memcpy(pipe, _pipe, sizeof(default_pipe));
 
/* TODO: JB should not be needed, but temporary backward reference */
switch (mode)
{
case IA_CSS_PIPE_MODE_PREVIEW:
pipe->mode = IA_CSS_PIPE_ID_PREVIEW;
-   pipe->pipe_settings.preview = IA_CSS_DEFAULT_PREVIEW_SETTINGS;
+   memcpy(>pipe_settings.preview, , sizeof(preview));
break;
case IA_CSS_PIPE_MODE_CAPTURE:
if (copy_pipe) {
@@ -2286,11 +2292,11 @@ init_pipe_defaults(enum ia_css_pipe_mode mode,
} else {
pipe->mode = IA_CSS_PIPE_ID_CAPTURE;
}
-   pipe->pipe_settings.capture = IA_CSS_DEFAULT_CAPTURE_SETTINGS;
+   memcpy(>pipe_settings.capture, , sizeof(capture));
break;
case IA_CSS_PIPE_MODE_VIDEO:
pipe->mode = IA_CSS_PIPE_ID_VIDEO;
-   pipe->pipe_settings.video = IA_CSS_DEFAULT_VIDEO_SETTINGS;
+   memcpy(>pipe_settings.video, , sizeof(video));
break;
case IA_CSS_PIPE_MODE_ACC:
pipe->mode = IA_CSS_PIPE_ID_ACC;
@@ -2300,7 +2306,7 @@ init_pipe_defaults(enum ia_css_pipe_mode mode,
break;
case IA_CSS_PIPE_MODE_YUVPP:
pipe->mode = IA_CSS_PIPE_ID_YUVPP;
-   pipe->pipe_settings.yuvpp = IA_CSS_DEFAULT_YUVPP_SETTINGS;
+   memcpy(>pipe_settings.yuvpp, , sizeof(yuvpp));
break;
default:
return IA_CSS_ERR_INVALID_ARGUMENTS;
-- 
2.26.2