2022-06-06 05:39:15

by Miaoqian Lin

Subject: [PATCH v2] powerpc/85xx: Fix reference leak in xes_mpc85xx_setup_arch

of_find_node_by_path() returns remote device nodepointer with
refcount incremented, we should use of_node_put() on it when done.
Add missing of_node_put() to avoid refcount leak.

Fixes: 3038acf9091f ("powerpc/85xx: Add platform support for X-ES MPC85xx boards")
Signed-off-by: Miaoqian Lin <[email protected]>
---
changes in v2:
- update Fixes tag.
v1 Link: https://lore.kernel.org/all/[email protected]
---
arch/powerpc/platforms/85xx/xes_mpc85xx.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/platforms/85xx/xes_mpc85xx.c b/arch/powerpc/platforms/85xx/xes_mpc85xx.c
index 5836e4ecb7a0..93f67b430714 100644
--- a/arch/powerpc/platforms/85xx/xes_mpc85xx.c
+++ b/arch/powerpc/platforms/85xx/xes_mpc85xx.c
@@ -130,6 +130,8 @@ static void __init xes_mpc85xx_setup_arch(void)
mpc85xx_smp_init();

fsl_pci_assign_primary();
+
+ of_node_put(root);
}

machine_arch_initcall(xes_mpc8572, mpc85xx_common_publish_devices);
--
2.25.1

2022-07-29 07:04:36

by Michael Ellerman

Subject: Re: [PATCH v2] powerpc/85xx: Fix reference leak in xes_mpc85xx_setup_arch

Miaoqian Lin <[email protected]> writes:
> of_find_node_by_path() returns remote device nodepointer with
> refcount incremented, we should use of_node_put() on it when done.
> Add missing of_node_put() to avoid refcount leak.
>
> Fixes: 3038acf9091f ("powerpc/85xx: Add platform support for X-ES MPC85xx boards")
> Signed-off-by: Miaoqian Lin <[email protected]>
> ---
> changes in v2:
> - update Fixes tag.
> v1 Link: https://lore.kernel.org/all/[email protected]
> ---
> arch/powerpc/platforms/85xx/xes_mpc85xx.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/powerpc/platforms/85xx/xes_mpc85xx.c b/arch/powerpc/platforms/85xx/xes_mpc85xx.c
> index 5836e4ecb7a0..93f67b430714 100644
> --- a/arch/powerpc/platforms/85xx/xes_mpc85xx.c
> +++ b/arch/powerpc/platforms/85xx/xes_mpc85xx.c
> @@ -130,6 +130,8 @@ static void __init xes_mpc85xx_setup_arch(void)
> mpc85xx_smp_init();
>
> fsl_pci_assign_primary();
> +
> + of_node_put(root);
> }

For context, here is the full function:

static void __init xes_mpc85xx_setup_arch(void)
{
struct device_node *root;
const char *model = "Unknown";

root = of_find_node_by_path("/");
if (root == NULL)
return;

model = of_get_property(root, "model", NULL);

printk(KERN_INFO "X-ES MPC85xx-based single-board computer: %s\n",
model + strlen("xes,"));

xes_mpc85xx_fixups();

mpc85xx_smp_init();

fsl_pci_assign_primary();
}


So yes it's missing an of_node_put(root).

But rather than add the of_node_put(), it would be simpler to just use
of_root directly, then it doesn't need an of_node_put() at all.

But then look closer. To begin with model is assigned "Unknown", but
then unconditionally overwritten by the of_get_property() call. So
that's a waste of space.

And then if there's no model property of_get_property() will return
NULL, and then the model + strlen("xes,") would oops.

And all of that just to print the model at boot, which is not really
necessary, anyone who cares can look it up in /proc/device-tree
after the system has booted.

So please just remove the lookup and printing of model entirely.

cheers