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SubjectRe: [PATCH] NULL struct irq_desc's member 'name' in dynamic_irq_cleanup()
On Thu, 16 Oct 2008 07:58:08 -0500
Dean Nelson <dcn@sgi.com> wrote:

> If the member 'name' of the irq_desc structure happens to point to a character
> string that is resident within a kernel module, problems insue if that module
> is rmmod'd (at which time dynamic_irq_cleanup() is called) and then later
> show_interrupts() is called by someone.

It would be nice to spell out what the "problems" are.

> It is also not a good thing if the
> character string resided in kmalloc'd space that has been kfree'd (after
> having called dynamic_irq_cleanup()). dynamic_irq_cleanup() fails to NULL
> the 'name' member and show_interrupts() references it on a few architectures
> (like h8300, sh and x86).
>
> Signed-off-by: Dean Nelson <dcn@sgi.com>
>
> ---
>
> kernel/irq/chip.c | 1 +
> 1 file changed, 1 insertion(+)
>
> Index: linux/kernel/irq/chip.c
> ===================================================================
> --- linux.orig/kernel/irq/chip.c 2008-10-15 07:44:31.000000000 -0500
> +++ linux/kernel/irq/chip.c 2008-10-16 06:55:56.000000000 -0500
> @@ -79,6 +79,7 @@ void dynamic_irq_cleanup(unsigned int ir
> desc->chip_data = NULL;
> desc->handle_irq = handle_bad_irq;
> desc->chip = &no_irq_chip;
> + desc->name = NULL;
> spin_unlock_irqrestore(&desc->lock, flags);
> }
>

Because we should work out whether this should be backported into
-stable. And if so, how far back it should go.



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