linux-kernel - Re: [PATCH 029/190] Revert "EDAC: Fix reference count leaks"

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Message-ID: <YIf8V9Q9FEWEPTsp@kroah.com>
Date:   Tue, 27 Apr 2021 13:58:15 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Borislav Petkov <bp@...e.de>
Cc:     linux-kernel@...r.kernel.org, Qiushi Wu <wu000273@....edu>
Subject: Re: [PATCH 029/190] Revert "EDAC: Fix reference count leaks"

On Wed, Apr 21, 2021 at 08:55:55PM +0200, Borislav Petkov wrote:
> On Wed, Apr 21, 2021 at 02:58:24PM +0200, Greg Kroah-Hartman wrote:
> > This reverts commit 17ed808ad243192fb923e4e653c1338d3ba06207.
> > 
> > Commits from @umn.edu addresses have been found to be submitted in "bad
> > faith" to try to test the kernel community's ability to review "known
> > malicious" changes.  The result of these submissions can be found in a
> > paper published at the 42nd IEEE Symposium on Security and Privacy
> > entitled, "Open Source Insecurity: Stealthily Introducing
> > Vulnerabilities via Hypocrite Commits" written by Qiushi Wu (University
> > of Minnesota) and Kangjie Lu (University of Minnesota).
> > 
> > Because of this, all submissions from this group must be reverted from
> > the kernel tree and will need to be re-reviewed again to determine if
> > they actually are a valid fix.  Until that work is complete, remove this
> > change to ensure that no problems are being introduced into the
> > codebase.
> > 
> > Cc: Qiushi Wu <wu000273@....edu>
> > Cc: Borislav Petkov <bp@...e.de>
> > Cc: https
> > Cc: https
> > Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> > ---
> >  drivers/edac/edac_device_sysfs.c | 1 -
> >  drivers/edac/edac_pci_sysfs.c    | 2 +-
> >  2 files changed, 1 insertion(+), 2 deletions(-)
> > 
> > diff --git a/drivers/edac/edac_device_sysfs.c b/drivers/edac/edac_device_sysfs.c
> > index 5e7593753799..0e7ea3591b78 100644
> > --- a/drivers/edac/edac_device_sysfs.c
> > +++ b/drivers/edac/edac_device_sysfs.c
> > @@ -275,7 +275,6 @@ 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);
> >  	module_put(edac_dev->owner);
> >  
> >  err_out:
> > diff --git a/drivers/edac/edac_pci_sysfs.c b/drivers/edac/edac_pci_sysfs.c
> > index 53042af7262e..72c9eb9fdffb 100644
> > --- a/drivers/edac/edac_pci_sysfs.c
> > +++ b/drivers/edac/edac_pci_sysfs.c
> > @@ -386,7 +386,7 @@ static int edac_pci_main_kobj_setup(void)
> >  
> >  	/* Error unwind statck */
> >  kobject_init_and_add_fail:
> > -	kobject_put(edac_pci_top_main_kobj);
> > +	kfree(edac_pci_top_main_kobj);
> >  
> >  kzalloc_fail:
> >  	module_put(THIS_MODULE);
> > -- 
> 
> That one is actually correct. 
> 
> AFAIR, that was a reaction to kobject_init_and_add()'s comment saying
> users should do kobject_put() when that function fails.
> 
> So the added kobject_put() would make sure the ->release method is
> called which will kfree the kobject and drop the module reference. And
> both ->release methods don't do anything else so there are no side
> effects from it like with other cases earlier today.
> 
> So yeah, that one could stay in.

Thanks for the review, now dropping.

greg k-h