Re: [PATCH v8 02/23] dma-pool: fix page leak in atomic_pool_expand() cleanup

[Leon Romanovsky <leon@kernel.org>]

On Fri, Jul 17, 2026 at 11:34:20PM +0530, Aneesh Kumar K.V (Arm) wrote:
> atomic_pool_expand() frees the allocated pages from the remove_mapping
> error path only when CONFIG_DMA_DIRECT_REMAP is enabled.
> 
> When CONFIG_DMA_DIRECT_REMAP is disabled, failures after page allocation,
> such as gen_pool_add_virt(), jump to remove_mapping and return without
> freeing the pages.
> 
> Move __free_pages(page, order) out of the CONFIG_DMA_DIRECT_REMAP block so
> that cleanup paths always release the allocation.
> 
> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
> Tested-by: Michael Kelley <mhklinux@outlook.com>
> Tested-by: Mostafa Saleh <smostafa@google.com>
> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
> ---
>  kernel/dma/pool.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
> index 2b2fbb709242..b0303efbc153 100644
> --- a/kernel/dma/pool.c
> +++ b/kernel/dma/pool.c
> @@ -81,6 +81,7 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
>  {
>  	unsigned int order;
>  	struct page *page = NULL;
> +	bool leak_pages = false;
>  	void *addr;
>  	int ret = -ENOMEM;
>  
> @@ -115,8 +116,10 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
>  	 */
>  	ret = set_memory_decrypted((unsigned long)page_to_virt(page),
>  				   1 << order);
> -	if (ret)
> +	if (ret) {
> +		leak_pages = true;
>  		goto remove_mapping;
> +	}
>  	ret = gen_pool_add_virt(pool, (unsigned long)addr, page_to_phys(page),
>  				pool_size, NUMA_NO_NODE);
>  	if (ret)
> @@ -130,14 +133,15 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
>  				   1 << order);
>  	if (WARN_ON_ONCE(ret)) {
>  		/* Decrypt succeeded but encrypt failed, purposely leak */
> -		goto out;
> +		leak_pages = true;

Instead of doing this dance with temporal variable, change "goto out" to
be "return true".

>  	}
>  remove_mapping:
>  #ifdef CONFIG_DMA_DIRECT_REMAP
>  	dma_common_free_remap(addr, pool_size);
>  free_page:

Remove free_page label, and change leftover of "goto free_page" to be
"goto out"

> -	__free_pages(page, order);
>  #endif
> +	if (!leak_pages)
> +		__free_pages(page, order);

Put these checks under out label and rely on page != NULL as a marker.
if (page)
 __free_pages(page, order);

>  out:
>  	return ret;
>  }
> -- 
> 2.43.0
> 
>