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SubjectRe: [PATCH v3] irqdomain: Prevent Oops in irq_domain_push_irq()
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On 08/25/2017 05:14 AM, Dan Carpenter wrote:
> This code generates a Smatch warning:
>
> kernel/irq/irqdomain.c:1511 irq_domain_push_irq()
> warn: variable dereferenced before check 'root_irq_data' (see line 1508)
>
> irq_get_irq_data() does sometimes return NULL pointers so this seems
> like a real bug. Let's fix this bug by moving the check for NULL
> earlier.
>
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Thanks for identifying and fixing this. It looks plausible, so if it
compiles without error you can add:

Acked-by: David Daney <david.daney@cavium.com>

> ---
> v2: Redo changelog.
> v3: Redo changelog again. Make it imperative.
>
> diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
> index b9c688944429..e84b7056bb08 100644
> --- a/kernel/irq/irqdomain.c
> +++ b/kernel/irq/irqdomain.c
> @@ -1505,10 +1505,10 @@ int irq_domain_push_irq(struct irq_domain *domain, int virq, void *arg)
> if (WARN_ON(!irq_domain_is_hierarchy(domain)))
> return -EINVAL;
>
> - if (domain->parent != root_irq_data->domain)
> + if (!root_irq_data)
> return -EINVAL;
>
> - if (!root_irq_data)
> + if (domain->parent != root_irq_data->domain)
> return -EINVAL;
>
> child_irq_data = kzalloc_node(sizeof(*child_irq_data), GFP_KERNEL,
>

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