Re: [PATCH] drm/amdgpu: Avoid integer overflow in amdgpu_device_suspend_display_audio

[Alex Deucher <alexdeucher@gmail.com>]

On Sat, May 2, 2020 at 4:35 AM Nathan Chancellor
<natechancellor@gmail.com> wrote:
>
> When building with Clang:
>
> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c:4160:53: warning: overflow in
> expression; result is -294967296 with type 'long' [-Winteger-overflow]
>                 expires = ktime_get_mono_fast_ns() + NSEC_PER_SEC * 4L;
>                                                                   ^
> 1 warning generated.
>
> Multiplication happens first due to order of operations and both
> NSEC_PER_SEC and 4 are long literals so the expression overflows. To
> avoid this, make 4 an unsigned long long literal, which matches the
> type of expires (u64).
>
> Fixes: 3f12acc8d6d4 ("drm/amdgpu: put the audio codec into suspend state before gpu reset V3")
> Link: https://github.com/ClangBuiltLinux/linux/issues/1017
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>

Applied.  Thanks!

Alex

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index 6f93af972b0a..caa38e7d502e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -4157,7 +4157,7 @@ static int amdgpu_device_suspend_display_audio(struct amdgpu_device *adev)
>                  * the audio controller default autosuspend delay setting.
>                  * 4S used here is guaranteed to cover that.
>                  */
> -               expires = ktime_get_mono_fast_ns() + NSEC_PER_SEC * 4L;
> +               expires = ktime_get_mono_fast_ns() + NSEC_PER_SEC * 4ULL;
>
>         while (!pm_runtime_status_suspended(&(p->dev))) {
>                 if (!pm_runtime_suspend(&(p->dev)))
>
> base-commit: fb9d670f57e3f6478602328bbbf71138be06ca4f
> --
> 2.26.2
>
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