Re: [PATCH] EDAC/sysfs: Fix calling kobject_put() without kobj initialization

[Harshit Mogalapalli]

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@xxxxxxxxxx>
> > ---
> > 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