Messages in this thread | | | Date | Tue, 29 May 2007 17:16:23 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] /proc/*/environ: wrong placing of ptrace_may_attach() check |
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On Mon, 28 May 2007 17:41:57 +0400 Alexey Dobriyan <adobriyan@sw.ru> wrote:
> Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Better changelogs, please.
> --- a/fs/proc/base.c > +++ b/fs/proc/base.c > @@ -204,12 +204,17 @@ static int proc_pid_environ(struct task_ > int res = 0; > struct mm_struct *mm = get_task_mm(task); > if (mm) { > - unsigned int len = mm->env_end - mm->env_start; > + unsigned int len; > + > + res = -ESRCH; > + if (!ptrace_may_attach(task)) > + goto out; > + > + len = mm->env_end - mm->env_start; > if (len > PAGE_SIZE) > len = PAGE_SIZE; > res = access_process_vm(task, mm->env_start, buffer, len, 0); > - if (!ptrace_may_attach(task)) > - res = -ESRCH; > +out: > mmput(mm); > } > return res;
What's wrong with the existing code? It's a bit dopey-looking and can, I guess, permit a task to cause a pagefault in an mm which it doesn't have permission to read from. But is there some more serious problem being fixed here?
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