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SubjectRe: [PATCH]: linux-2.6.21-uc0 (MMU-less updates)
Robin Getz wrote:
> On Wed 2 May 2007 07:32, Greg Ungerer pondered:
>> Robin Getz wrote:
>>> On Wed 2 May 2007 01:23, Greg Ungerer pondered:
>>>> diff -Naur linux-2.6.21/fs/namei.c linux-2.6.21-uc0/fs/namei.c
>>>> --- linux-2.6.21/fs/namei.c 2007-05-01 17:12:53.000000000 +1000
>>>> +++ linux-2.6.21-uc0/fs/namei.c 2007-05-01 17:16:18.000000000 +1000
>>>> @@ -120,12 +120,14 @@
>>>> int retval;
>>>> unsigned long len = PATH_MAX;
>>>>
>>>> +#ifdef CONFIG_MMU
>>>> if (!segment_eq(get_fs(), KERNEL_DS)) {
>>>> if ((unsigned long) filename >= TASK_SIZE)
>>>> return -EFAULT;
>>>> if (TASK_SIZE - (unsigned long) filename < PATH_MAX)
>>>> len = TASK_SIZE - (unsigned long) filename;
>>>> }
>>>> +#endif
>>>>
>>>> retval = strncpy_from_user(page, filename, len);
>>>> if (retval > 0) {
>>> I was trying to understand why we don't want to do the same checking on
>>> noMMU?
>> The problem is on systems that have RAM mapped at high physical
>> addresses. TASK_SIZE may well be a numerically smaller number
>> than the address range that RAM sits in. So this test fails when
>> it shouldn't.
>
> So, then this is a problem only on one or two architectures, not all noMMU
> platforms?

Its not an architecture problem. It can effect any board that
has RAM mapped at a large numerical addresses (larger than TASK_SIZE).
So it can effect any non-MMU platform.

Regards
Greg



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Greg Ungerer -- Chief Software Dude EMAIL: gerg@snapgear.com
SnapGear -- a Secure Computing Company PHONE: +61 7 3435 2888
825 Stanley St, FAX: +61 7 3891 3630
Woolloongabba, QLD, 4102, Australia WEB: http://www.SnapGear.com
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