linux-kernel - Re: [PATCH] of: dynamic: Fix potential memory leak in of_changeset

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Message-ID: <CAL_JsqJB_pK-Q-Y-v6mWV1KwfL8sjFGgCcSL5gdrZm-TqxvBJg@mail.gmail.com>
Date:   Fri, 8 Sep 2023 10:18:37 -0500
From:   Rob Herring <robh@...nel.org>
To:     Dan Carpenter <dan.carpenter@...aro.org>,
        kbuild test robot <lkp@...el.com>
Cc:     Frank Rowand <frowand.list@...il.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] of: dynamic: Fix potential memory leak in of_changeset_action()

On Fri, Sep 8, 2023 at 2:03 AM Dan Carpenter <dan.carpenter@...aro.org> wrote:
>
> Smatch complains that the error path where "action" is invalid leaks
> the "ce" allocation:
>     drivers/of/dynamic.c:935 of_changeset_action()
>     warn: possible memory leak of 'ce'
>
> Fix this by doing the validation before the allocation.

I'm going to add a note when applying that "action" can't ever
actually be invalid because all the callers are static inlines with
hardcoded action values. I suppose there could be an out of tree
module calling of_changeset_action() directly, but that's wrong given
the wrappers.

> Fixes: 914d9d831e61 ("of: dynamic: Refactor action prints to not use "%pOF" inside devtree_lock")
> Reported-by: kernel test robot <lkp@...el.com>
> Closes: https://lore.kernel.org/r/202309011059.EOdr4im9-lkp@intel.com/

Despite what that says, it was never reported to me. IOW, the added TO
and CC lines don't seem to have any effect.

> Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
> ---
>  drivers/of/dynamic.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
> index 0a3483e247a8..f63250c650ca 100644
> --- a/drivers/of/dynamic.c
> +++ b/drivers/of/dynamic.c
> @@ -890,13 +890,13 @@ int of_changeset_action(struct of_changeset *ocs, unsigned long action,
>  {
>         struct of_changeset_entry *ce;
>
> +       if (WARN_ON(action >= ARRAY_SIZE(action_names)))
> +               return -EINVAL;
> +
>         ce = kzalloc(sizeof(*ce), GFP_KERNEL);
>         if (!ce)
>                 return -ENOMEM;
>
> -       if (WARN_ON(action >= ARRAY_SIZE(action_names)))
> -               return -EINVAL;
> -
>         /* get a reference to the node */
>         ce->action = action;
>         ce->np = of_node_get(np);
> --
> 2.39.2
>