Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <1562872923-2463-1-git-send-email-wang6495@umn.edu>
In-Reply-To: <1562872923-2463-1-git-send-email-wang6495@umn.edu>
From:   Ming Lei <tom.leiming@gmail.com>
Date:   Fri, 12 Jul 2019 08:33:43 +0800
Message-ID: <CACVXFVNkdgxddQiJn1SMQSuOL8E_PCLRhkv8XPLUg=5tdmpiLA@mail.gmail.com>
Subject: Re: [PATCH v2] block/bio-integrity: fix a memory leak bug
To:     Wenwen Wang <wang6495@umn.edu>
Cc:     Wenwen Wang <wenwen@cs.uga.edu>, Jens Axboe <axboe@kernel.dk>,
        "open list:BLOCK LAYER" <linux-block@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Fri, Jul 12, 2019 at 3:29 AM Wenwen Wang <wang6495@umn.edu> wrote:
>
> From: Wenwen Wang <wenwen@cs.uga.edu>
>
> In bio_integrity_prep(), a kernel buffer is allocated through kmalloc() to
> hold integrity metadata. Later on, the buffer will be attached to the bio
> structure through bio_integrity_add_page(), which returns the number of
> bytes of integrity metadata attached. Due to unexpected situations,
> bio_integrity_add_page() may return 0. As a result, bio_integrity_prep()
> needs to be terminated with 'false' returned to indicate this error.
> However, the allocated kernel buffer is not freed on this execution path,
> leading to a memory leak.
>
> To fix this issue, free the allocated buffer before returning from
> bio_integrity_prep().
>
> Signed-off-by: Wenwen Wang <wenwen@cs.uga.edu>
> ---
>  block/bio-integrity.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/block/bio-integrity.c b/block/bio-integrity.c
> index 4db6208..fb95dbb 100644
> --- a/block/bio-integrity.c
> +++ b/block/bio-integrity.c
> @@ -276,8 +276,12 @@ bool bio_integrity_prep(struct bio *bio)
>                 ret = bio_integrity_add_page(bio, virt_to_page(buf),
>                                              bytes, offset);
>
> -               if (ret == 0)
> -                       return false;
> +               if (ret == 0) {
> +                       printk(KERN_ERR "could not attach integrity payload\n");
> +                       kfree(buf);
> +                       status = BLK_STS_RESOURCE;
> +                       goto err_end_io;
> +               }
>
>                 if (ret < bytes)
>                         break;

Looks fine:

Reviewed-by: Ming Lei <ming.lei@redhat.com>


Thanks,
Ming Lei