linux-kernel - [PATCH] mailbox: zynq-ipi: fix error handling while device

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Date:   Thu, 10 Nov 2022 23:08:22 +0800
From:   Yang Yingliang <yangyingliang@...wei.com>
To:     <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
CC:     <jassisinghbrar@...il.com>, <michal.simek@...inx.com>
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@...wei.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