Messages in this thread | | | From | Dmitry Vyukov <> | Date | Mon, 28 Sep 2015 18:08:34 +0200 | Subject | Re: [PATCH] arch/x86: fix out-of-bounds in get_wchan() |
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On Mon, Sep 28, 2015 at 5:40 PM, Andrey Ryabinin <ryabinin.a.a@gmail.com> wrote: > 2015-09-28 12:00 GMT+03:00 Dmitry Vyukov <dvyukov@google.com>: >> 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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