[PATCH] of: drop a reference on error in __of_attach_node_sysfs()

[PATCH] of: drop a reference on error in __of_attach_node_sysfs()

[Dan Carpenter]

We add a new of_node_get() to this function, but we should drop the
reference if kobject_add().

Fixes: 5b2c2f5a0ea3 ("of: overlay: add missing of_node_get() in __of_attach_node_sysfs")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
From static analysis.  Maybe we should just call of_node_get() right
before we return 0?

 drivers/of/kobj.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/of/kobj.c b/drivers/of/kobj.c
index c72eef988041..a90dc4b3b060 100644
--- a/drivers/of/kobj.c
+++ b/drivers/of/kobj.c
@@ -138,8 +138,10 @@ int __of_attach_node_sysfs(struct device_node *np)
 
 	rc = kobject_add(&np->kobj, parent, "%s", name);
 	kfree(name);
-	if (rc)
+	if (rc) {
+		of_node_put(np);
 		return rc;
+	}
 
 	for_each_property_of_node(np, pp)
 		__of_add_property_sysfs(np, pp);
-- 
2.26.2

Re: [PATCH] of: drop a reference on error in __of_attach_node_sysfs()

[Michael Ellerman]

Dan Carpenter <dan.carpenter@oracle.com> writes:
> We add a new of_node_get() to this function, but we should drop the
> reference if kobject_add().
                            ^
                            fails?
>
> Fixes: 5b2c2f5a0ea3 ("of: overlay: add missing of_node_get() in __of_attach_node_sysfs")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> From static analysis.  Maybe we should just call of_node_get() right
> before we return 0?

Yeah that would be simpler and equally correct AFAICS.

cheers

> diff --git a/drivers/of/kobj.c b/drivers/of/kobj.c
> index c72eef988041..a90dc4b3b060 100644
> --- a/drivers/of/kobj.c
> +++ b/drivers/of/kobj.c
> @@ -138,8 +138,10 @@ int __of_attach_node_sysfs(struct device_node *np)
>  
>  	rc = kobject_add(&np->kobj, parent, "%s", name);
>  	kfree(name);
> -	if (rc)
> +	if (rc) {
> +		of_node_put(np);
>  		return rc;
> +	}
>  
>  	for_each_property_of_node(np, pp)
>  		__of_add_property_sysfs(np, pp);
> -- 
> 2.26.2

[PATCH v2] of: Fix a refcounting bug in __of_attach_node_sysfs()

[Dan Carpenter]

The problem in this code is that if kobject_add() fails, then it should
call of_node_put(np) to drop the reference count.  I've actually moved
the of_node_get(np) later in the function to avoid needing to do clean
up.

Fixes: 5b2c2f5a0ea3 ("of: overlay: add missing of_node_get() in __of_attach_node_sysfs")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
v2: move the of_node_get() instead of doing clean up.  Also the v1 had a
    confusing typo in the commit message.

 drivers/of/kobj.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/of/kobj.c b/drivers/of/kobj.c
index c72eef988041..a32e60b024b8 100644
--- a/drivers/of/kobj.c
+++ b/drivers/of/kobj.c
@@ -134,8 +134,6 @@ int __of_attach_node_sysfs(struct device_node *np)
 	if (!name)
 		return -ENOMEM;
 
-	of_node_get(np);
-
 	rc = kobject_add(&np->kobj, parent, "%s", name);
 	kfree(name);
 	if (rc)
@@ -144,6 +142,7 @@ int __of_attach_node_sysfs(struct device_node *np)
 	for_each_property_of_node(np, pp)
 		__of_add_property_sysfs(np, pp);
 
+	of_node_get(np);
 	return 0;
 }
 
-- 
2.26.2

Re: [PATCH v2] of: Fix a refcounting bug in __of_attach_node_sysfs()

[Rob Herring]

On Wed, 20 May 2020 15:04:14 +0300, Dan Carpenter wrote:
> The problem in this code is that if kobject_add() fails, then it should
> call of_node_put(np) to drop the reference count.  I've actually moved
> the of_node_get(np) later in the function to avoid needing to do clean
> up.
> 
> Fixes: 5b2c2f5a0ea3 ("of: overlay: add missing of_node_get() in __of_attach_node_sysfs")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> v2: move the of_node_get() instead of doing clean up.  Also the v1 had a
>     confusing typo in the commit message.
> 
>  drivers/of/kobj.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 

Applied, thanks!