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Message-ID: <9ad01578-9982-fd55-14a3-a74bf0906165@huawei.com>
Date: Thu, 8 Dec 2022 21:53:20 +0800
From: Yang Yingliang <yangyingliang@...wei.com>
To: <lee@...nel.org>, <krzysztof.kozlowski@...onical.com>
CC: <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mfd: core: fix UAF while using device of node
Hi,
On 2022/11/16 15:41, Yang Yingliang wrote:
> I got the following UAF report:
>
> refcount_t: underflow; use-after-free.
> WARNING: CPU: 1 PID: 270 at lib/refcount.c:29 refcount_warn_saturate+0x121/0x180
> ...
> OF: ERROR: memory leak, expected refcount 1 instead of -1073741824,
> of_node_get()/of_node_put() unbalanced - destroy cset entry:
> attach overlay node /i2c/pmic@...powerkey
>
> The of_node of device assigned in mfd_match_of_node_to_dev() need be
> get, and it will be put in platform_device_release().
>
> Fixes: 002be8114007 ("mfd: core: Add missing of_node_put for loop iteration")
> Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
Is this patch good or do you have any suggestion ?
Thanks,
Yang
> ---
> drivers/mfd/mfd-core.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
> index 16d1861e9682..8e57f67719cf 100644
> --- a/drivers/mfd/mfd-core.c
> +++ b/drivers/mfd/mfd-core.c
> @@ -161,7 +161,7 @@ static int mfd_match_of_node_to_dev(struct platform_device *pdev,
> of_entry->np = np;
> list_add_tail(&of_entry->list, &mfd_of_node_list);
>
> - pdev->dev.of_node = np;
> + pdev->dev.of_node = of_node_get(np);
> pdev->dev.fwnode = &np->fwnode;
> #endif
> return 0;
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