NACK: [SRU][J][PATCH 1/1] i3c: master: cdns: Fix use after free vulnerability in cdns_i3c_master Driver Due to Race Condition

[Massimiliano Pellizzer]

On Tue, 16 Sept 2025 at 17:07, Alice C. Munduruca
<alice.munduruca at canonical.com> wrote:
>
> From: Kaixin Wang <kxwang23 at m.fudan.edu.cn>
>
> In the cdns_i3c_master_probe function, &master->hj_work is bound with
> cdns_i3c_master_hj. And cdns_i3c_master_interrupt can call
> cnds_i3c_master_demux_ibis function to start the work.
>
> If we remove the module which will call cdns_i3c_master_remove to
> make cleanup, it will free master->base through i3c_master_unregister
> while the work mentioned above will be used. The sequence of operations
> that may lead to a UAF bug is as follows:
>
> CPU0                                      CPU1
>
>                                      | cdns_i3c_master_hj
> cdns_i3c_master_remove               |
> i3c_master_unregister(&master->base) |
> device_unregister(&master->dev)      |
> device_release                       |
> //free master->base                  |
>                                      | i3c_master_do_daa(&master->base)
>                                      | //use master->base
>
> Fix it by ensuring that the work is canceled before proceeding with
> the cleanup in cdns_i3c_master_remove.
>
> Signed-off-by: Kaixin Wang <kxwang23 at m.fudan.edu.cn>
> Link: https://lore.kernel.org/r/20240911153544.848398-1-kxwang23@m.fudan.edu.cn
> Signed-off-by: Alexandre Belloni <alexandre.belloni at bootlin.com>
> (backported from commit 609366e7a06d035990df78f1562291c3bf0d4a12)
> [cremfuelled: given commit `0f74f8b` is missing, add hunk before func]
> [cremfuelled: `i3c_master_unregister` which is non-void.]

The two lines above should be merged in the following format:
[cremfuelled: given commit `0f74f8b` is missing, add hunk before func
 `i3c_master_unregister` which is non-void.]

Other than this, the patch looks good.
Please modify the commit message and sand again.

-- 
Massimiliano Pellizzer

> CVE-2024-50061
> Signed-off-by: Alice C. Munduruca <alice.munduruca at canonical.com>
> ---
>  drivers/i3c/master/i3c-master-cdns.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/i3c/master/i3c-master-cdns.c b/drivers/i3c/master/i3c-master-cdns.c
> index b9cfda6ae9ae..4473c0b1ae2e 100644
> --- a/drivers/i3c/master/i3c-master-cdns.c
> +++ b/drivers/i3c/master/i3c-master-cdns.c
> @@ -1668,6 +1668,7 @@ static int cdns_i3c_master_remove(struct platform_device *pdev)
>         struct cdns_i3c_master *master = platform_get_drvdata(pdev);
>         int ret;
>
> +       cancel_work_sync(&master->hj_work);
>         ret = i3c_master_unregister(&master->base);
>         if (ret)
>                 return ret;
> --
> 2.48.1
>
>
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