On Sun, Sep 21, 2014 at 08:51:44AM -0700, Guenter Roeck wrote:
> Commit 8c86e70acead ("resource: provide new functions to walk through
> resources") adds a suble new requirement that iomem_resource.child must
> not be NULL when walk_system_ram_range is called. This can cause a crash
> if it turns out that there are no children. The crash ('Unable to handle
> kernel NULL pointer dereference') is seen when trying to test a crisv32
> image on kernels with this commit applied.
>
> Fix by adding a NULL check into next_resource().
>
> Fixes: 8c86e70acead ("resource: provide new functions to walk through
> resources")
Hi Guenter,
Can you please provide backtrace of the crash.
Thanks
Vivek
> Cc: Vivek Goyal <vgo...@redhat.com>
> Cc: Andrew Morton <a...@linux-foundation.org>
> Signed-off-by: Guenter Roeck <li...@roeck-us.net>
> ---
> The NULL check could be added elsewhere instead. I am open to suggestions.
>
> kernel/resource.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/kernel/resource.c b/kernel/resource.c
> index 60c5a38..00c57ad 100644
> --- a/kernel/resource.c
> +++ b/kernel/resource.c
> @@ -61,6 +61,9 @@ static DEFINE_SPINLOCK(bootmem_resource_lock);
>
> static struct resource *next_resource(struct resource *p, bool sibling_only)
> {
> + if (p == NULL)
> + return NULL;
> +
> /* Caller wants to traverse through siblings only */
> if (sibling_only)
> return p->sibling;
> --
> 1.9.1
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