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

Nathan Chancellor
2020-05-30T02:57:40Z

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 <arnd@arndb.de>

Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>

> ---
> 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, &default_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->pipe_settings.preview, &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->pipe_settings.capture, &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->pipe_settings.video, &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->pipe_settings.yuvpp, &yuvpp, sizeof(yuvpp));
> break;
> default:
> return IA_CSS_ERR_INVALID_ARGUMENTS;
> --
> 2.26.2
>