| Re: [PATCH] /proc/*/environ: wrong placing of ptrace_may_attach() check [message #13559 is a reply to message #13500] |
Wed, 30 May 2007 00:16   |
Andrew Morton
Messages: 127
Registered: December 2005
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Senior Member |
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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?
I shouldn't have to ask this stuff.
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