Re: [PATCH v6 1/4] cacheinfo: Check for null last-level cache info

[Ricardo Neri]

On Wed, Sep 11, 2024 at 04:05:09PM +0200, Borislav Petkov wrote:
> On Wed, Sep 04, 2024 at 11:00:33PM -0700, Ricardo Neri wrote:
> > Before determining the validity of the last-level cache info, ensure that
> > it has been allocated. Simply checking for non-zero cache_leaves() is not
> > sufficient, as some architectures (e.g., Intel processors) have non-zero
> > cache_leaves() before allocation.
> >
> > Dereferencing NULL cacheinfo can occur in update_per_cpu_data_slice_size().
> > This function iterates over all online CPUs. However, a CPU may have come
> > online recently, but its cacheinfo may not have been allocated yet.
> > 
> > Reviewed-by: Andreas Herrmann <aherrmann@xxxxxxx>
> > Reviewed-by: Sudeep Holla <sudeep.holla@xxxxxxx>
> > Tested-by: Andreas Herrmann <aherrmann@xxxxxxx>
> > Signed-off-by: Ricardo Neri <ricardo.neri-calderon@xxxxxxxxxxxxxxx>
> 
> While at it, pls fix the formatting insanity of allocate_cache_info() into:
> 
> static inline int allocate_cache_info(int cpu)
> {
>         per_cpu_cacheinfo(cpu) = kcalloc(cache_leaves(cpu), sizeof(struct cacheinfo), GFP_ATOMIC);
>         if (!per_cpu_cacheinfo(cpu)) {
>                 cache_leaves(cpu) = 0;
>                 return -ENOMEM;
>         }
>             
>         return 0;
> }
> 
> Thx.

Sure! I can do this. I assume this should be a separate patch.