Re: [PATCH] mailbox: zynq-ipi: fix error handling while device_register()

From: Tanmay Shah <tanmay.shah@amd.com>
To: <yangyingliang@huawei.com>
Cc: <jassisinghbrar@gmail.com>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>, <michal.simek@amd.com>,
	<tanmay.shah@amd.com>
Subject: Re: [PATCH] mailbox: zynq-ipi: fix error handling while device_register()
Date: Thu, 22 Dec 2022 18:50:26 -0800	[thread overview]
Message-ID: <20221223025025.2107945-1-tanmay.shah@amd.com> (raw)
In-Reply-To: <20221110150822.392385-1-yangyingliang@huawei.com>

Reviewed-by: Tanmay Shah <tanmay.shah@amd.com>

Thanks for your patch! This looks good to me.

(Updated: Fixed Subject of the reply)

>From: Yang Yingliang <yangyingliang@huawei.com>
>Date: Thu, 10 Nov 2022 23:08:22 +0800
>Subject: [PATCH] mailbox: zynq-ipi: fix error handling while device_register()
> fails
>
>If device_register() fails, it has two issues:
>1. The name allocated by dev_set_name() is leaked.
>2. The parent of device is not NULL, device_unregister() is called
>   in zynqmp_ipi_free_mboxes(), it will lead a kernel crash because
>   of removing not added device.
>
>Call put_device() to give up the reference, so the name is freed in
>kobject_cleanup(). Add device registered check in zynqmp_ipi_free_mboxes()
>to avoid null-ptr-deref.
>
>Fixes: 4981b82ba2ff ("mailbox: ZynqMP IPI mailbox controller")
>Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
>---
> drivers/mailbox/zynqmp-ipi-mailbox.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/mailbox/zynqmp-ipi-mailbox.c b/drivers/mailbox/zynqmp-ipi-mailbox.c
>index 31a0fa914274..12e004ff1a14 100644
>--- a/drivers/mailbox/zynqmp-ipi-mailbox.c
>+++ b/drivers/mailbox/zynqmp-ipi-mailbox.c
>@@ -493,6 +493,7 @@ static int zynqmp_ipi_mbox_probe(struct zynqmp_ipi_mbox *ipi_mbox,
> 	ret = device_register(&ipi_mbox->dev);
> 	if (ret) {
> 		dev_err(dev, "Failed to register ipi mbox dev.\n");
>+		put_device(&ipi_mbox->dev);
> 		return ret;
> 	}
> 	mdev = &ipi_mbox->dev;
>@@ -619,7 +620,8 @@ static void zynqmp_ipi_free_mboxes(struct zynqmp_ipi_pdata *pdata)
> 		ipi_mbox = &pdata->ipi_mboxes[i];
> 		if (ipi_mbox->dev.parent) {
> 			mbox_controller_unregister(&ipi_mbox->mbox);
>-			device_unregister(&ipi_mbox->dev);
>+			if (device_is_registered(&ipi_mbox->dev))
>+				device_unregister(&ipi_mbox->dev);
> 		}
> 	}
> }
>
>-- 
>2.25.1