Re: [PATCH v2] sparc: kernel/sbus.c: fix memory leakage

[Richard Mortimer]

On 17/01/2013 11:56, Cong Ding wrote:
> On Thu, Jan 17, 2013 at 10:41:59AM +0000, Richard Mortimer wrote:
> > On 16/01/2013 22:01, Cong Ding wrote:
> > > the variable iommu and strbuf are not freed if it goes to error.
> > >
> > > Signed-off-by: Cong Ding <dinggnu@xxxxxxxxx>
> > > ---
> > >   arch/sparc/kernel/sbus.c |    2 ++
> > >   1 file changed, 2 insertions(+)
> > >
> > > diff --git a/arch/sparc/kernel/sbus.c b/arch/sparc/kernel/sbus.c
> > > index 1271b3a..78aa26b 100644
> > > --- a/arch/sparc/kernel/sbus.c
> > > +++ b/arch/sparc/kernel/sbus.c
> > > @@ -656,6 +656,8 @@ static void __init sbus_iommu_init(struct platform_device *op)
> > >   	return;
> > >
> > >   fatal_memory_error:
> > > +	kfree(strbuf);
> >
> > strbuf will be uninitialized if the iommu allocation fails. I don't
> > have a particular preference for how to fix this but tend to dislike
> > initial assignment with NULL because it hides other control flow
> > issues.
> Sorry I didn't notice strbuf will be uninitialized here. But if we don't
> initially assign a NULL value to strbuf, I cannot find a way to handle it
> besides the first version patch. Did you have any suggestions? For me, I like
> the first version.

Two thoughts...

1 - just use a goto target for the iommu allocation failure and make 
that skip the strbuf free call. The others use the existing 
fatal_memory_error label.

2 - Move the strbuf kzalloc up 2 lines so that it occurs before the test 
for iommu.

2b - In case (2) above the failure test could be changed to
if (!iommu || !strbuf)
to remove duplication of goto.

I'd probably go for 2/2b to address Sam's initial comment.

Regards

Richard


> - cong
> > Regards
> >
> > Richard
> >
> > > +	kfree(iommu);
> > >   	prom_printf("sbus_iommu_init: Fatal memory allocation error.\n");
> > >   }
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