linux-kernel - Re: [PATCH][next] fs: dlm: Fix memory leak of object mh

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Date:   Wed, 26 May 2021 10:19:49 -0400
From:   Alexander Ahring Oder Aring <aahringo@...hat.com>
To:     Colin King <colin.king@...onical.com>
Cc:     Christine Caulfield <ccaulfie@...hat.com>,
        David Teigland <teigland@...hat.com>, cluster-devel@...hat.com,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] fs: dlm: Fix memory leak of object mh

Hi,

On Wed, May 26, 2021 at 9:40 AM Colin King <colin.king@...onical.com> wrote:
>
> From: Colin Ian King <colin.king@...onical.com>
>
> There is an error return path that is not kfree'ing mh after
> it has been successfully allocates.  Fix this by free'ing it.
>
> Addresses-Coverity: ("Resource leak")
> Fixes: a070a91cf140 ("fs: dlm: add more midcomms hooks")
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  fs/dlm/rcom.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/fs/dlm/rcom.c b/fs/dlm/rcom.c
> index 085f21966c72..19298edc1573 100644
> --- a/fs/dlm/rcom.c
> +++ b/fs/dlm/rcom.c
> @@ -393,6 +393,7 @@ static void receive_rcom_lookup(struct dlm_ls *ls, struct dlm_rcom *rc_in)
>         if (rc_in->rc_id == 0xFFFFFFFF) {
>                 log_error(ls, "receive_rcom_lookup dump from %d", nodeid);
>                 dlm_dump_rsb_name(ls, rc_in->rc_buf, len);
> +               kfree(mh);
>                 return;

This seems to be a bigger issue, we cannot revert the buffer
allocation with a kfree, we cannot revert it at all. We should avoid
any error handling between create_rcom() and send_rcom(). In general
between get_buffer/commit_buffer.

I don't see a problem with moving the error handling before
create_rcom(). That should fix the issue.

- Alex