linux-kernel - Re: [PATCH] EDAC/sysfs: Fix calling kobject

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Date:   Tue, 28 Nov 2023 23:25:14 +0530
From:   Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Borislav Petkov <bp@...en8.de>, Tony Luck <tony.luck@...el.com>,
        James Morse <james.morse@....com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Robert Richter <rric@...nel.org>, linux-edac@...r.kernel.org,
        linux-kernel@...r.kernel.org, dan.carpenter@...aro.org,
        kernel-janitors@...r.kernel.org, error27@...il.com
Subject: Re: [PATCH] EDAC/sysfs: Fix calling kobject_put() without kobj
 initialization

Hi Greg,

On 28/11/23 9:58 pm, Greg Kroah-Hartman wrote:
> On Tue, Nov 28, 2023 at 05:09:52AM -0800, Harshit Mogalapalli wrote:
>> In edac_pci_main_kobj_setup() when dev_root is NULL,
>> kobject_init_and_add() is not called.
>>
>>          if (err) { // err = -ENODEV;
>>                  edac_dbg(1, "Failed to register '.../edac/pci'\n");
>>                  goto kobject_init_and_add_fail; // call to kobject_put()
>>          }
>>
>> This will cause a runtime warning in kobject_put() if the above happens.
>> Warning:
>> "kobject: '%s' (%p): is not initialized, yet kobject_put() is being called."
>>
>> Fix the error handling to avoid the above possible situation.
>>
>> Fixes: cb4a0bec0bb9 ("EDAC/sysfs: move to use bus_get_dev_root()")
>> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
>> ---
>> This is based on static analysis with Smatch and only compile tested.
>> ---
>>   drivers/edac/edac_pci_sysfs.c | 14 ++++++++------
>>   1 file changed, 8 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/edac/edac_pci_sysfs.c b/drivers/edac/edac_pci_sysfs.c
>> index 901d4cd3ca38..71a0d4b9c2cf 100644
>> --- a/drivers/edac/edac_pci_sysfs.c
>> +++ b/drivers/edac/edac_pci_sysfs.c
>> @@ -370,12 +370,14 @@ static int edac_pci_main_kobj_setup(void)
>>   
>>   	/* Instanstiate the pci object */
>>   	dev_root = bus_get_dev_root(edac_subsys);
>> -	if (dev_root) {
>> -		err = kobject_init_and_add(edac_pci_top_main_kobj,
>> -					   &ktype_edac_pci_main_kobj,
>> -					   &dev_root->kobj, "pci");
>> -		put_device(dev_root);
>> -	}
>> +	if (!dev_root)
>> +		goto kzalloc_fail;
>> +
>> +	err = kobject_init_and_add(edac_pci_top_main_kobj,
>> +				   &ktype_edac_pci_main_kobj,
>> +				   &dev_root->kobj, "pci");
>> +	put_device(dev_root);
>> +
>>   	if (err) {
>>   		edac_dbg(1, "Failed to register '.../edac/pci'\n");
>>   		goto kobject_init_and_add_fail;
>> -- 
>> 2.39.3
>>
> 
> Hi,
> 
> This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
> a patch that has triggered this response.  He used to manually respond
> to these common problems, but in order to save his sanity (he kept
> writing the same thing over and over, yet to different people), I was
> created.  Hopefully you will not take offence and will fix the problem
> in your patch and resubmit it so that it can be accepted into the Linux
> kernel tree.
> 
> You are receiving this message because of the following common error(s)
> as indicated below:
> 
> - This looks like a new version of a previously submitted patch, but you
>    did not list below the --- line any changes from the previous version.
>    Please read the section entitled "The canonical patch format" in the
>    kernel file, Documentation/process/submitting-patches.rst for what
>    needs to be done here to properly describe this.
> 
> - You have marked a patch with a "Fixes:" tag for a commit that is in an
>    older released kernel, yet you do not have a cc: stable line in the
>    signed-off-by area at all, which means that the patch will not be
>    applied to any older kernel releases.  To properly fix this, please
>    follow the documented rules in the
>    Documentation/process/stable-kernel-rules.rst file for how to resolve
>    this.
> 
> If you wish to discuss this problem further, or you have questions about
> how to resolve this issue, please feel free to respond to this email and
> Greg will reply once he has dug out from the pending patches received
> from other developers.

No, this is a similar bug but in the edac_pci_sysfs.c file instead of 
the edac_device_sysfs.c.

Let me resend these two patches as a patchset and change the subject to 
make it more obvious(EDAC/pci_sysfs, EDAC/device_sysfs in title).  And 
add a CC stable tag.

Thanks,
Harshit

> 
> thanks,
> 
> greg k-h's patch email bot