linux-kernel - Re: [PATCH] mm/gup: Fix memory leaks in __gup_benchmark

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Date:   Mon, 25 Nov 2019 10:25:12 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Navid Emamdoost <navid.emamdoost@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     emamd001@....edu
Subject: Re: [PATCH] mm/gup: Fix memory leaks in __gup_benchmark_ioctl

On 22.11.19 23:41, Navid Emamdoost wrote:
> In the implementation of __gup_benchmark_ioctl() memory is leaked if the
> passed cmd is invalid. Release pages before returning -1.
> 
> Fixes: 714a3a1ebafe ("mm/gup_benchmark.c: add additional pinning methods")



> Signed-off-by: Navid Emamdoost <navid.emamdoost@...il.com>
> ---
>  mm/gup_benchmark.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/gup_benchmark.c b/mm/gup_benchmark.c
> index 7dd602d7f8db..33ede5727523 100644
> --- a/mm/gup_benchmark.c
> +++ b/mm/gup_benchmark.c
> @@ -23,7 +23,7 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
>  		struct gup_benchmark *gup)
>  {
>  	ktime_t start_time, end_time;
> -	unsigned long i, nr_pages, addr, next;
> +	unsigned long i, j, nr_pages, addr, next;
>  	int nr;
>  	struct page **pages;
>  
> @@ -63,6 +63,12 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
>  					    NULL);
>  			break;
>  		default:
> +			for (j = 0; j < i; j++) {
> +				if (!pages[j])
> +					break;
> +				put_page(pages[j]);
> +			}

We didn't pin any pages, why should we release them?

IMHO, all that's needed is the ...

> +			kvfree(pages);

.. here


>  			return -1;
>  		}
>  

Not sure how often CONFIG_GUP_BENCHMARK is really enabled. Maybe we should

Cc: stable@...r.kernel.org # v4.20+


With only the kvfree(pages)

Reviewed-by: David Hildenbrand <david@...hat.com>

-- 

Thanks,

David / dhildenb