Re: [PATCH v2 2/5] mm/kmsan: skip vunmap_range_noflush when KMSAN is disabled

[Dev Jain <dev.jain@arm.com>]

On 19/10/26 11:15 am, Hao Ge wrote:
> kmsan_vmap_pages_range_noflush() returns 0 when kmsan_enabled is
> false.  The unmap side does not, so it still walks the shadow and
> origin page tables even though KMSAN never installed any metadata
> there.
> 
> Add the matching early return.
> 
> Reported-by: Sashiko <sashiko-bot@kernel.org>
> Cc: stable@vger.kernel.org

Cc stable without fixes?

I guess without the fix nothing is actually wrong, except doing
wasteful work?


> Signed-off-by: Hao Ge <hao.ge@linux.dev>
> ---
>  mm/kmsan/hooks.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/mm/kmsan/hooks.c b/mm/kmsan/hooks.c
> index a706666db097..107f66841274 100644
> --- a/mm/kmsan/hooks.c
> +++ b/mm/kmsan/hooks.c
> @@ -138,6 +138,9 @@ static unsigned long vmalloc_origin(unsigned long addr)
>  
>  void kmsan_vunmap_range_noflush(unsigned long start, unsigned long end)
>  {
> +	if (!kmsan_enabled)
> +		return;
> +
>  	__vunmap_range_noflush(vmalloc_shadow(start), vmalloc_shadow(end));
>  	__vunmap_range_noflush(vmalloc_origin(start), vmalloc_origin(end));
>  	flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));