linux-kernel - Re: [PATCH] block: do not leak memory in bio_copy_user

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Date:   Wed, 10 Apr 2019 22:13:14 +0000
From:   Chaitanya Kulkarni <Chaitanya.Kulkarni@....com>
To:     "jglisse@...hat.com" <jglisse@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Jens Axboe <axboe@...nel.dk>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH] block: do not leak memory in bio_copy_user_iov()

Looks good.

Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@....com>

On 04/10/2019 01:28 PM, jglisse@...hat.com wrote:
> From: Jérôme Glisse <jglisse@...hat.com>
>
> When bio_add_pc_page() fails in bio_copy_user_iov() we should free
> the page we just allocated otherwise we are leaking it.
>
> Signed-off-by: Jérôme Glisse <jglisse@...hat.com>
> Cc: Jens Axboe <axboe@...nel.dk>
> Cc: linux-block@...r.kernel.org
> Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> Cc: stable@...r.kernel.org
> ---
>   block/bio.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/block/bio.c b/block/bio.c
> index b64cedc7f87c..716510ecd7ff 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -1298,8 +1298,11 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
>   			}
>   		}
>
> -		if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes)
> +		if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes) {
> +			if (!map_data)
> +				__free_page(page);
>   			break;
> +		}
>
>   		len -= bytes;
>   		offset = 0;
>