linux-kernel - Re: [PATCH] tpm: Do not dereference NULL pointer if acpi_os_map

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Date:	Thu, 16 Aug 2012 00:02:40 +0200 (CEST)
From:	Jesper Juhl <jj@...osbits.net>
To:	Kent Yoder <key@...ux.vnet.ibm.com>
cc:	linux-kernel@...r.kernel.org, tpmdd-devel@...ts.sourceforge.net,
	Sirrix AG <tpmdd@...rix.com>,
	Marcel Selhorst <tpmdd@...horst.net>,
	Rajiv Andrade <mail@...jiv.net>,
	Seiji Munetoh <munetoh@...ibm.com>,
	Stefan Berger <stefanb@...ibm.com>,
	Reiner Sailer <sailer@...son.ibm.com>,
	Kylene Hall <kjhall@...ibm.com>
Subject: Re: [PATCH] tpm: Do not dereference NULL pointer if acpi_os_map_memory()
 fails.

On Wed, 15 Aug 2012, Kent Yoder wrote:

> Hi Jesper,
> 
> > > Unfortunately we just get NULL back, so we can't really tell the user
> > > exactely what went wrong, but we can at least avoid crashing and
> > > return an error (-EIO seemed more generic and more suitable here than
> > > -ENOMEM or something else, so I picked that).
> > 
> > Thanks Jesper. I'd made some updates to tpm_bios.c recently but this
> > should still apply. I'll let you know if not.
> 
>   Of course I'm wrong here, this code moved over into tpm_acpi.c. If you
> can resubmit on top of my staging tree, I will apply it there.
> 

No problem. I'll have that patch for you in a moment when I'm done 
fetching your tree.


> git://github.com/shpedoikal/linux.git v3.6-rc1-tpmdd-staging
> 
> > > Signed-off-by: Jesper Juhl <jj@...osbits.net>
> > > ---
> > >  drivers/char/tpm/tpm_bios.c | 5 +++++
> > >  1 file changed, 5 insertions(+)
> > > 
> > >   Compile tested only.
> > > 
> > > diff --git a/drivers/char/tpm/tpm_bios.c b/drivers/char/tpm/tpm_bios.c
> > > index 0636520..0c5c274 100644
> > > --- a/drivers/char/tpm/tpm_bios.c
> > > +++ b/drivers/char/tpm/tpm_bios.c
> > > @@ -410,6 +410,11 @@ static int read_log(struct tpm_bios_log *log)
> > >  	log->bios_event_log_end = log->bios_event_log + len;
> > > 
> > >  	virt = acpi_os_map_memory(start, len);
> > > +	if (!virt) {
> 
>   Also please add kfree(log->bios_event_log); in this error path.
> 
Whoops, of course, will do.


-- 
Jesper Juhl <jj@...osbits.net>       http://www.chaosbits.net/
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