linux-kernel - Re: [PATCH] remoteproc: core: Remove casting to rproc_handle_resource

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Message-ID: <CABCJKudwajnmHAEC1XAH=pouCoOXq7q6NmpLST5pba8ejU6FtA@mail.gmail.com>
Date:   Mon, 22 Feb 2021 14:46:14 -0800
From:   Sami Tolvanen <samitolvanen@...gle.com>
To:     Jindong Yue <jindong.yue@....com>
Cc:     ohad@...ery.com, bjorn.andersson@...aro.org,
        linux-remoteproc@...r.kernel.org, Peng Fan <peng.fan@....com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] remoteproc: core: Remove casting to rproc_handle_resource_t

Hi,

On Sun, Feb 21, 2021 at 11:18 PM Jindong Yue <jindong.yue@....com> wrote:
>
> There are four different callback functions that are used for the
> rproc_handle_resource_t callback that all have different second
> parameter types.
>
> rproc_handle_vdev -> struct fw_rsc_vdev
> rproc_handle_trace -> struct fw_rsc_trace
> rproc_handle_devmem -> struct fw_rsc_devmem
> rproc_handle_carveout -> struct fw_rsc_carveout
>
> These callbacks are cast to rproc_handle_resource_t so that there is no
> error about incompatible pointer types. Unfortunately, this is a control
> flow integrity violation, which verifies that the callback function's
> types match the prototypes exactly before jumping.

Thank you for sending the patch! It might be worth noting that Clang's
Control-Flow Integrity checking is currently used only in Android
kernels, so while the type mismatches are real and should be fixed,
they don't result in runtime errors without this feature.

> To fix this, change the second parameter of all functions to void * and
> use a local variable with the correct type so that everything works
> properly. With this, we can remove casting to rproc_handle_resource_t
> for these functions.
>
> Signed-off-by: Jindong Yue <jindong.yue@....com>
> Reviewed-by: Peng Fan <peng.fan@....com>

This looks correct to me. Please feel free to add:

Reviewed-by: Sami Tolvanen <samitolvanen@...gle.com>

Sami