On Mon, Sep 28, 2015 at 5:40 PM, Andrey Ryabinin <[email protected]> wrote:
> 2015-09-28 12:00 GMT+03:00 Dmitry Vyukov <[email protected]>:
>> stack = (unsigned long)task_stack_page(p);
>> - if (p->thread.sp < stack || p->thread.sp >= stack+THREAD_SIZE)
>> + /* The task can be already running at this point, so tread
>> carefully. */
>> + fp = READ_ONCE(p->thread.sp);
>> + if (fp < stack || fp >= stack+THREAD_SIZE)
>
> Since we deference fp, it should be "|| fp + sizeof(u64) >= stack +
> THREAD_SIZE"
Good point.
I guess it should be "|| fp + sizeof(u64) > stack + THREAD_SIZE",
because == is OK if we add 8.
>> return 0;
>> - fp = *(u64 *)(p->thread.sp);
>> + fp = READ_ONCE(*(u64 *)fp);
>> do {
>> if (fp < (unsigned long)stack ||
>> - fp >= (unsigned long)stack+THREAD_SIZE)
>> + fp+8 >= (unsigned long)stack+THREAD_SIZE)
>
> The same as above;
> 'fp+8 +sizeof(u64) >= ...'
>
>> return 0;
>> - ip = *(u64 *)(fp+8);
>> + ip = READ_ONCE(*(u64 *)(fp+8));
>>
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