Re: [PATCH] amba: fix refcount underflow if amba_device_add() fails

On 2022/5/24 11:09, Guenter Roeck wrote:

On Tue, May 24, 2022 at 10:51:39AM +0800, Kefeng Wang wrote:

quoted

"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@roeck-us.net>
Signed-off-by: Kefeng Wang <redacted>

Tested-by: Guenter Roeck <linux@roeck-us.net>

Thanks.

PS: I also test with kmemleak, this could also fix previous memory leak issue.

Thanks,
Guenter

quoted

---
  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

.

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