Re: [PATCH net] page_pool: Fix use-after-free in page_pool_recycle_in_ring

[Paolo Abeni <pabeni@redhat.com>]

On 5/23/25 8:45 AM, Dong Chenchen wrote:
> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> index 7745ad924ae2..08f1b000ebc1 100644
> --- a/net/core/page_pool.c
> +++ b/net/core/page_pool.c
> @@ -707,19 +707,16 @@ void page_pool_return_page(struct page_pool *pool, netmem_ref netmem)
>  
>  static bool page_pool_recycle_in_ring(struct page_pool *pool, netmem_ref netmem)
>  {
> +	bool in_softirq;
>  	int ret;
>  	/* BH protection not needed if current is softirq */
> -	if (in_softirq())
> -		ret = ptr_ring_produce(&pool->ring, (__force void *)netmem);
> -	else
> -		ret = ptr_ring_produce_bh(&pool->ring, (__force void *)netmem);
> -
> -	if (!ret) {
> +	in_softirq = page_pool_producer_lock(pool);
> +	ret = !__ptr_ring_produce(&pool->ring, (__force void *)netmem);
> +	if (ret)
>  		recycle_stat_inc(pool, ring);
> -		return true;
> -	}

Does not build in our CI:

net/core/page_pool.c: In function ‘page_pool_recycle_in_ring’:
net/core/page_pool.c:750:45: error: suggest braces around empty body in
an ‘if’ statement [-Werror=empty-body]
  750 |                 recycle_stat_inc(pool, ring);
      |                                             ^

/P