Re: [PATCH -next] lib: fix test_hmm.c reference after free

[Ralph Campbell]

On 6/17/20 10:31 PM, Randy Dunlap wrote:
> From: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
>
> Coccinelle scripts report the following errors:
>
> lib/test_hmm.c:523:20-26: ERROR: reference preceded by free on line 521
> lib/test_hmm.c:524:21-27: ERROR: reference preceded by free on line 521
> lib/test_hmm.c:523:28-35: ERROR: devmem is NULL but dereferenced.
> lib/test_hmm.c:524:29-36: ERROR: devmem is NULL but dereferenced.
>
> Fix these by using the local variable 'res' instead of devmem.
>
> Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
> Cc: JÃrÃme Glisse <jglisse@xxxxxxxxxx>
> Cc: linux-mm@xxxxxxxxx
> Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
> ---
>   lib/test_hmm.c |    3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
>
> --- linux-next-20200617.orig/lib/test_hmm.c
> +++ linux-next-20200617/lib/test_hmm.c
> @@ -520,8 +520,7 @@ static bool dmirror_allocate_chunk(struc
>   err_free:
>   	kfree(devmem);
>   err_release:
> -	release_mem_region(devmem->pagemap.res.start,
> -			   resource_size(&devmem->pagemap.res));
> +	release_mem_region(res->start, resource_size(res));
>   err:
>   	mutex_unlock(&mdevice->devmem_lock);
>   	return false;

Thanks for fixing this!
Reviewed-by: Ralph Campbell <rcampbell@xxxxxxxxxx>