On Thu, 2006-11-16 at 17:42, bibo,mao wrote:
> Tony,
> please discard this patch. It can not fix completely. If ptrace
> caller wants to access vforked child process's user rbs, there
> will be problem.
The patch is correct.
If ptracer wants to access vforked child process's user rbs,
find_thread_for_addr's first parameter, child, will points to
the vforked task_struct instead of vforker's.
>
> thanks
> bibo,mao
>
> bibo,mao wrote:
> > hi,
> > I encountered one problem when running ptrace test case, the
> > situation is this: traced process's syscall parameter needs to
> > be accessed, but for sys_clone system call with clone_flag
> > (CLONE_VFORK | CLONE_VM | SIGCHLD) parameter. this syscall's
> > parameter accessing result is wrong.
> > The reason is that with clone_flag(CLONE_VFORK | CLONE_VM | SIGCHLD),
> > cloned thread's mm point is the same, but tgid is different.
> > without this patch find_thread_for_addr will return cloned thread,
> > but not the thread which call sys_clone syscall.
> >
> > thanks
> > bibo,mao
> >
> > --- 2.6.19-rc5.org/arch/ia64/kernel/ptrace.c 2006-11-16 16:23:31.000000000 +0800
> > +++ 2.6.19-rc5/arch/ia64/kernel/ptrace.c 2006-11-16 16:25:07.000000000 +0800
> > @@ -607,7 +607,7 @@ find_thread_for_addr (struct task_struct
> > */
> > list_for_each_safe(this, next, ¤t->children) {
> > p = list_entry(this, struct task_struct, sibling);
> > - if (p->mm != mm)
> > + if (p->tgid != child->tgid)
> > continue;
> > if (thread_matches(p, addr)) {
> > child = p;
> > -
-
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