Re: [LKML] [tip:x86/urgent] x86: Fix NULL pointer access in irq_force_complete_move() for Xen guests

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Fri, Apr 30, 2010 at 09:36:42PM +0000, tip-bot for Prarit Bhargava wrote:
> Commit-ID:  bbd391a15d82e14efe9d69ba64cadb855b061dba
> Gitweb:     http://git.kernel.org/tip/bbd391a15d82e14efe9d69ba64cadb855b061dba
> Author:     Prarit Bhargava <prarit@redhat.com>
> AuthorDate: Tue, 27 Apr 2010 11:24:42 -0400
> Committer:  H. Peter Anvin <hpa@zytor.com>
> CommitDate: Fri, 30 Apr 2010 14:31:38 -0700
> 
> x86: Fix NULL pointer access in irq_force_complete_move() for Xen guests
> 
> Upstream PV guests fail to boot because of a NULL pointer in
> irq_force_complete_move().  It is possible that xen guests have
> irq_desc->chip_data = NULL.
> 
> Test for NULL chip_data pointer before attempting to complete an irq move.
> 
> Signed-off-by: Prarit Bhargava <prarit@redhat.com>
> LKML-Reference: <20100427152434.16193.49104.sendpatchset@prarit.bos.redhat.com>
> Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
> Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

> Cc: <stable@kernel.org> [2.6.33]
> ---
>  arch/x86/kernel/apic/io_apic.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
> index 127b871..eb2789c 100644
> --- a/arch/x86/kernel/apic/io_apic.c
> +++ b/arch/x86/kernel/apic/io_apic.c
> @@ -2545,6 +2545,9 @@ void irq_force_complete_move(int irq)
>  	struct irq_desc *desc = irq_to_desc(irq);
>  	struct irq_cfg *cfg = desc->chip_data;
>  
> +	if (!cfg)
> +		return;
> +
>  	__irq_complete_move(&desc, cfg->vector);
>  }
>  #else
> --
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