Re: [PATCH] irq: fix possible null-pointer deref irq_domain_to_irq

[Jamie Iles]

Hi Rob,

On Wed, Nov 23, 2011 at 12:23:08PM +0000, Jamie Iles wrote:
> On Thu, Nov 10, 2011 at 07:37:32AM -0600, Rob Herring wrote:
> > On 11/10/2011 05:14 AM, Jamie Iles wrote:
> > > On Thu, Nov 10, 2011 at 10:53:03AM +0000, Jamie Iles wrote:
> > >> It is optional for an irqdomain to have a to_irq() method, and for
> > >> simple domains they often don't require any operations at all - just
> > >> hwirq to Linux irq translation.  Check we have valid ops before
> > >> dereferencing them.
> > >>
> > >> Patch originally by Rob Herring.
> > >>
> > >> Suggested-by: Rob Herring <robherring2@xxxxxxxxx>
> > > 
> > > Naturally git send-email doesn't know how to convert this into a CC, so 
> > > Rob is now CC'd!
> > > 
> > > Jamie
> > > 
> > >> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > >> Cc: Grant Likely <grant.likely@xxxxxxxxxxxx>
> > >> Signed-off-by: Jamie Iles <jamie@xxxxxxxxxxxxx>
> > >> ---
> > >>
> > >> Rob, I can't see that you've already posted this but I didn't want to
> > >> hold Marc's GIC patches up.
> > 
> > Thanks. I didn't get around to it yesterday.
> > 
> > Acked-by: Rob Herring <rob.herring@xxxxxxxxxxx>
> 
> I've just noticed in kernel/irq/irqdomain.c, that the kerneldoc for 
> irq_domain_add() says that a valid ops structure is required, so perhaps 
> this fix isn't right and we should just have an empty ops structure for 
> simple controllers...

I wonder if this might make more sense instead.  I'll post a proper 
patch if you think so.

Regards,

Jamie

diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 200ce83..92c3484 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -143,11 +143,6 @@ int irq_domain_simple_dt_translate(struct irq_domain *d,
 	return 0;
 }
 
-struct irq_domain_ops irq_domain_simple_ops = {
-	.dt_translate = irq_domain_simple_dt_translate,
-};
-EXPORT_SYMBOL_GPL(irq_domain_simple_ops);
-
 /**
  * irq_domain_create_simple() - Set up a 'simple' translation range
  */
@@ -181,4 +176,11 @@ void irq_domain_generate_simple(const struct of_device_id *match,
 		pr_info("no node found\n");
 }
 EXPORT_SYMBOL_GPL(irq_domain_generate_simple);
+#else /* CONFIG_OF_IRQ */
+#define irq_domain_simple_dt_translate NULL
 #endif /* CONFIG_OF_IRQ */
+
+struct irq_domain_ops irq_domain_simple_ops = {
+	.dt_translate = irq_domain_simple_dt_translate,
+};
+EXPORT_SYMBOL_GPL(irq_domain_simple_ops);
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