From: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Tony Luck <tony.luck@intel.com>,
James Morse <james.morse@arm.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Robert Richter <rric@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-edac@vger.kernel.org, linux-kernel@vger.kernel.org,
dan.carpenter@linaro.org, kernel-janitors@vger.kernel.org,
error27@gmail.com, stable@vger.kernel.org
Subject: Re: [PATCH v2 1/2] EDAC/device_sysfs: Fix calling kobject_put() with ->state_initialized unset
Date: Thu, 25 Jan 2024 19:50:49 +0530 [thread overview]
Message-ID: <287bfc4e-2de8-47ea-b638-7349143ab4c9@oracle.com> (raw)
In-Reply-To: <20240125130936.GYZbJdkFOQds9w0hAp@fat_crate.local>
On 25/01/24 6:39 pm, Borislav Petkov wrote:
> On Tue, Nov 28, 2023 at 10:30:35AM -0800, Harshit Mogalapalli wrote:
>> In edac_device_register_sysfs_main_kobj(), when dev_root is NULL,
>
Thanks for checking this.
> When is dev_root NULL?
>
> A real use case or this is just from code staring?
>
This is based on static analysis, not real testing.
>> diff --git a/drivers/edac/edac_device_sysfs.c b/drivers/edac/edac_device_sysfs.c
>> index 010c26be5846..4cac14cbdb60 100644
>> --- a/drivers/edac/edac_device_sysfs.c
>> +++ b/drivers/edac/edac_device_sysfs.c
>> @@ -253,11 +253,13 @@ int edac_device_register_sysfs_main_kobj(struct edac_device_ctl_info *edac_dev)
>>
>> /* register */
>> dev_root = bus_get_dev_root(edac_subsys);
>> - if (dev_root) {
>> - err = kobject_init_and_add(&edac_dev->kobj, &ktype_device_ctrl,
>> - &dev_root->kobj, "%s", edac_dev->name);
>
> What cb4a0bec0bb9 did looks wrong. That if (err) check should be inside
> the if (dev_root).
>
> IOW, that function's error checking needs balancing. Something like
> this below.
>
> And looking at the other one, it has the same issue...
>
> ---
> diff --git a/drivers/edac/edac_device_sysfs.c b/drivers/edac/edac_device_sysfs.c
> index 237a542e045a..3476ef13e681 100644
> --- a/drivers/edac/edac_device_sysfs.c
> +++ b/drivers/edac/edac_device_sysfs.c
> @@ -228,8 +228,8 @@ static struct kobj_type ktype_device_ctrl = {
> */
> int edac_device_register_sysfs_main_kobj(struct edac_device_ctl_info *edac_dev)
> {
> - struct device *dev_root;
> const struct bus_type *edac_subsys;
> + struct device *dev_root;
> int err = -ENODEV;
>
> edac_dbg(1, "\n");
> @@ -243,26 +243,26 @@ int edac_device_register_sysfs_main_kobj(struct edac_device_ctl_info *edac_dev)
> /* Init the devices's kobject */
> memset(&edac_dev->kobj, 0, sizeof(struct kobject));
>
> - /* Record which module 'owns' this control structure
> - * and bump the ref count of the module
> + /*
> + * Record which module 'owns' this control structure and bump
> + * the ref count of the module
> */
> edac_dev->owner = THIS_MODULE;
>
> if (!try_module_get(edac_dev->owner))
> goto err_out;
>
> - /* register */
> dev_root = bus_get_dev_root(edac_subsys);
> - if (dev_root) {
> - err = kobject_init_and_add(&edac_dev->kobj, &ktype_device_ctrl,
> - &dev_root->kobj, "%s", edac_dev->name);
> - put_device(dev_root);
> - }
> + if (!dev_root)
> + goto err_module;
> +
> + err = kobject_init_and_add(&edac_dev->kobj, &ktype_device_ctrl,
> + &dev_root->kobj, "%s", edac_dev->name);
> if (err) {
> - edac_dbg(1, "Failed to register '.../edac/%s'\n",
> - edac_dev->name);
> + edac_dbg(1, "Failed to register '.../edac/%s'\n", edac_dev->name);
> goto err_kobj_reg;
> }
> +
> kobject_uevent(&edac_dev->kobj, KOBJ_ADD);
>
> /* At this point, to 'free' the control struct,
> @@ -273,9 +273,11 @@ int edac_device_register_sysfs_main_kobj(struct edac_device_ctl_info *edac_dev)
>
> return 0;
>
> - /* Error exit stack */
> err_kobj_reg:
> kobject_put(&edac_dev->kobj);
> + put_device(dev_root);
In this diff, put_device(dev_root) is not called on the success path. I
checked couple of other callers of bus_get_dev_root() and they call
put_device(dev_root) after using dev_root. I think we need to have
put_device() on the success path as well.
> +
> +err_module:
> module_put(edac_dev->owner);
>
An alternate diff could be:
diff --git a/drivers/edac/edac_device_sysfs.c
b/drivers/edac/edac_device_sysfs.c
index 237a542e045a..0c8e66e40af8 100644
--- a/drivers/edac/edac_device_sysfs.c
+++ b/drivers/edac/edac_device_sysfs.c
@@ -275,7 +275,8 @@ int edac_device_register_sysfs_main_kobj(struct
edac_device_ctl_info *edac_dev)
/* Error exit stack */
err_kobj_reg:
- kobject_put(&edac_dev->kobj);
+ if(dev_root)
+ kobject_put(&edac_dev->kobj);
module_put(edac_dev->owner);
err_out:
Thanks,
Harshit
> err_out:
>
prev parent reply other threads:[~2024-01-25 14:21 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-28 18:30 [PATCH v2 1/2] EDAC/device_sysfs: Fix calling kobject_put() with ->state_initialized unset Harshit Mogalapalli
2023-11-28 18:30 ` [PATCH v2 2/2] EDAC/pci_sysfs: " Harshit Mogalapalli
2024-01-22 6:56 ` [PATCH v2 1/2] EDAC/device_sysfs: " Harshit Mogalapalli
2024-01-25 13:09 ` Borislav Petkov
2024-01-25 14:20 ` Harshit Mogalapalli [this message]
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