linux-kernel - [PATCH] amba: fix refcount underflow if amba_device

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Date:   Tue, 24 May 2022 10:51:39 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     <linux@...linux.org.uk>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
CC:     <robh@...nel.org>, Kefeng Wang <wangkefeng.wang@...wei.com>,
        Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH] amba: fix refcount underflow if amba_device_add() fails

"ARM: 9192/1: amba: fix memory leak in amba_device_try_add()" leads
to a refcount underflow if amba_device_add() fails, which called by
of_amba_device_create(), the of_amba_device_create() already exists
the error handling, so amba_put_device() only need to be added into
amba_deferred_retry().

Reported-by: Guenter Roeck <linux@...ck-us.net>
Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
---
 drivers/amba/bus.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index 0e3ed5eb367b..0cb20324da16 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -493,13 +493,8 @@ static int amba_device_try_add(struct amba_device *dev, struct resource *parent)
 		goto skip_probe;
 
 	ret = amba_read_periphid(dev);
-	if (ret) {
-		if (ret != -EPROBE_DEFER) {
-			amba_device_put(dev);
-			goto err_out;
-		}
+	if (ret)
 		goto err_release;
-	}
 
 skip_probe:
 	ret = device_add(&dev->dev);
@@ -546,6 +541,7 @@ static int amba_deferred_retry(void)
 			continue;
 
 		list_del_init(&ddev->node);
+		amba_device_put(ddev->dev);
 		kfree(ddev);
 	}
 
-- 
2.35.3