Re: [RFC][PATCH] x86/hpet: fix NULL pointer dereference in msi_domain_alloc_irqs()

[Jiang Liu]

On 2015/5/12 12:14, Sergey Senozhatsky wrote:
>> directly call __irq_domain_alloc_irqs() in hpet_assign_irq() and pass
>> correct `arg' to fix the oops.
>>
> 
> oh, what I was thinking about... it should be as simple as this.
> 
> 8<-----8<-----
> 
> From 8be2eb548cefc788c87b05da22176b7360c6aca9 Mon Sep 17 00:00:00 2001
> From: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
> Date: Mon, 11 May 2015 18:56:49 +0900
> Subject: [PATCH] x86/hpet: fix NULL pointer deference in
>  msi_domain_alloc_irqs()
> 
> Fix the following oops:
>  hpet_msi_get_hwirq+0x1f/0x27
>  msi_domain_alloc+0x35/0xfe
>  ? trace_hardirqs_on_caller+0x16c/0x188
>  irq_domain_alloc_irqs_recursive+0x51/0x95
>  __irq_domain_alloc_irqs+0x151/0x223
>  hpet_assign_irq+0x5d/0x68
>  hpet_msi_capability_lookup+0x121/0x1cb
>  ? hpet_enable+0x2b4/0x2b4
>  hpet_late_init+0x5f/0xf2
>  ? hpet_enable+0x2b4/0x2b4
>  do_one_initcall+0x184/0x199
>  kernel_init_freeable+0x1af/0x237
>  ? rest_init+0x13a/0x13a
>  kernel_init+0xe/0xd4
>  ret_from_fork+0x3f/0x70
>  ? rest_init+0x13a/0x13a
> 
> since 3cb96f0c9733 ('x86/hpet: Enhance HPET IRQ to support hierarchical
> irqdomains') hpet_msi_capability_lookup() uses hpet_assign_irq(). the
> latter discards `irq_alloc_info info' param and instead passes NULL to
> __irq_domain_alloc_irqs() as `arg'. __irq_domain_alloc_irqs() invokes
> irq_domain_alloc_irqs_recursive(), which msi_domain_alloc_irqs() and,
> eventually, accesses `arg->hpet_index' in hpet_msi_get_hwirq().
> 
> pass a correct `irq_alloc_info info' pointer to irq_domain_alloc_irqs()
> in hpet_assign_irq() to fix the oops.
> 
> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
> ---
>  arch/x86/kernel/apic/msi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/apic/msi.c b/arch/x86/kernel/apic/msi.c
> index 58fde66..ef516af 100644
> --- a/arch/x86/kernel/apic/msi.c
> +++ b/arch/x86/kernel/apic/msi.c
> @@ -351,6 +351,6 @@ int hpet_assign_irq(struct irq_domain *domain, struct hpet_dev *dev,
>  	info.hpet_id = hpet_dev_id(domain);
>  	info.hpet_index = dev_num;
>  
> -	return irq_domain_alloc_irqs(domain, 1, NUMA_NO_NODE, NULL);
> +	return irq_domain_alloc_irqs(domain, 1, NUMA_NO_NODE, &info);
>  }
>  #endif
Hi Sergey,
	My fault, I have prepared 'info' without actually passing it to
irq_domain_alloc_irqs().
	Thanks for fixing it.
	Reviewed-by: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>

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