On Mon, Nov 09, 2020 at 04:57:29PM +0100, Christian König wrote:
> Am 09.11.20 um 16:16 schrieb Ville Syrjälä:
> > On Wed, Nov 11, 2020 at 06:13:02PM +0100, Christian König wrote:
> >> Am 09.11.20 um 01:54 schrieb Dave Airlie:
> >>> @@ -1432,15 +1479,18 @@ int ttm_bo_swapout(struct ttm_operation_ctx *ctx)
> >>> if (bo->mem.mem_type != TTM_PL_SYSTEM) {
> >>> struct ttm_operation_ctx ctx = { false, false };
> >>> struct ttm_resource evict_mem;
> >>> + struct ttm_place hop = {};
> >> Please always use memset() if you want to zero initialize something in
> >> the kernel, we had enough trouble with that.
> > What trouble is that? I've not heard of anything, and we use
> > ={} quite extensively in drm land.
>
> ={} initializes only named fields, not padding.
Has that actually happened?
>
> The result is that for example when doing a hash or CRC of a structure
> you can come up with different results depending on the architecture
> and/or structure layout.
>
> Another problem are information leaks from the kernel to userspace
> because of this.
>
> Because of this Mesa for example strongly discourages using ={} for
> zeroing a structure.
>
> Regards,
> Christian.
--
Ville Syrjälä
Intel
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