linux-kernel - Re: [PATCH v3 0/2] pci: endpoint: Fix double free in pci_epf

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Date:   Tue, 27 Feb 2018 13:11:57 +0100 (CET)
From:   Rolf Evers-Fischer <embedded24@...rs-fischer.de>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>
cc:     Rolf Evers-Fischer <embedded24@...rs-fischer.de>, kishon@...com,
        bhelgaas@...gle.com, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, andy.shevchenko@...il.com
Subject: Re: [PATCH v3 0/2] pci: endpoint: Fix double free in
 pci_epf_create()

Hello Lorenzo,

On Tue, 27 Feb 2018, Lorenzo Pieralisi wrote:

> On Tue, Feb 27, 2018 at 11:02:28AM +0100, Rolf Evers-Fischer wrote:
> > This is version 3 of a patchset to avoid double free in function
> > 'pci_epf_create()'.
> > 
> > When I accidentally created a new endpoint device with an empty name,
> > the kernel warned about "attempted to be registered with empty name!"
> > and crashed afterwards.
> > 
> > It turned out that the crash was not caused by the 'device_add()'
> > function itself, but by a double kfree of 'epf->name' and 'epf'.
> > 
> > The first patch just simplifies the code, while the second patch
> > fixes the problem.
> > 
> > Changes in v3:
> > - Matched to other pending pci endpoint commits (thanks, Bjorn!)
> > - Added "Fixes" tag in patch 2 (thanks, Andy!)
> > 
> > Changes in v2:
> > - Based on feedback from Lorenzo, Andy and Kishon (thanks!)
> > - Change IDs removed
> > - First patch completely reworked in order to eliminate the
> >   need for the second 'kstrdup' allocation and the 'kfree' of
> >   the first allocation.
> >   It was tested with name="pci_epf_test.0" and name="pci_epb":
> >   The 'epf->name' was "pci_epf_test" or "pci_epb" (=unchanged).
> > 
> > Rolf Evers-Fischer (2):
> >   pci: endpoint: Simplify name allocation for epf device
> >   pci: endpoint: Fix kernel panic after put_device()
>     ^^^
> 
> s/pci/PCI
> 
> Bjorn pointed that out too, I can do it when merging the patches myself
> just a hint in case you have to respin it again, no problem.
> 

thank you for pointing this out. I haven't recognized this detail. I 
thought that Bjorn wanted me to rebase my patch series upon the latest 
unmerged PCI endpoint patches - and I was surprised that there was no 
change.

Thank you for your kind offer to fix it when merging the patches.

Best regards,
 Rolf