Re: [PATCH] omap: pm: Fix overflow when doing powerdomain deps lookups.

[Kevin Hilman <khilman@deeprootsystems.com>]

Mike Chan <mike@android.com> writes:

> On Tue, Aug 11, 2009 at 7:38 AM, Kevin
> Hilman<khilman@deeprootsystems.com> wrote:
>> Mike Chan <mike@android.com> writes:
>>
>>> Signed-off-by: Mike Chan <mike@android.com>
>>> ---
>>>  arch/arm/mach-omap2/powerdomain.c |    2 +-
>>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/arch/arm/mach-omap2/powerdomain.c b/arch/arm/mach-omap2/powerdomain.c
>>> index 0334609..6077629 100644
>>> --- a/arch/arm/mach-omap2/powerdomain.c
>>> +++ b/arch/arm/mach-omap2/powerdomain.c
>>> @@ -90,7 +90,7 @@ static struct powerdomain *_pwrdm_deps_lookup(struct powerdomain *pwrdm,
>>>       if (!pwrdm || !deps || !omap_chip_is(pwrdm->omap_chip))
>>>               return ERR_PTR(-EINVAL);
>>>
>>> -     for (pd = deps; pd; pd++) {
>>> +     for (pd = deps; pd->pwrdm_name; pd++) {
>>
>> Maybe should be:
>>
>>        for (pd = deps; pd && pd->pwrdm_name; pd++) {
>>
>
> At the end of the list pd is a pointer to a NULL struct, so checking
> if the address == NULL doesn't help here. In fact the original code
> will just keep running past the struct to read who knows what in
> memory.

I see that now, didn't notice the NULL struct terminators.

> This case manifests itself when from clkdms_setup() when enabling auto
> idle for a clock domain and the clockdomain usecount is greater than
> 0. When _clkdm_add_autodeps() tries to add the a dependency that does
> not exist in the powerdomain->wkdep_srcs array the for loop will run
> past the wkdep_srcs array.

Thanks, will add this as changelog and push to PM branch as well as
pm-2.6.29.

Kevin

> Currently in linux-omap you won't hit this because the not found case
> is never executed, unless you start modifying powerdomains and their
> wakeup/sleep deps.
>
> --Mike
>
>> ?
>>
>>>
>>>               if (!omap_chip_is(pd->omap_chip))
>>>                       continue;
>>
>> Also, a descriptive changelog would be helpful here describing the
>> conditions where you saw overflow etc.
>>
>> Kevin
>>
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