Messages in this thread | | | Date | Wed, 14 Mar 2007 09:59:21 +0000 | From | "Catalin Marinas" <> | Subject | Re: Possible "struct pid" leak from tty_io.c |
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On 13/03/07, Eric W. Biederman <ebiederm@xmission.com> wrote: > "Catalin Marinas" <catalin.marinas@gmail.com> writes: > > void proc_clear_tty(struct task_struct *p) > > { > > + struct tty_struct *tty; > > + > > spin_lock_irq(&p->sighand->siglock); > > + tty = p->signal->tty; > > + if (tty) { > > + put_pid(tty->session); > > + put_pid(tty->pgrp); > > + } > > p->signal->tty = NULL; > > spin_unlock_irq(&p->sighand->siglock); > > } > > This patch can't be right. Not the way proc_clear_tty is called > once for each process in the session, plus we aren't clearing > tty->session and tty->pgrp here. > > If the above patch works it's a fluke.
I looked at the logs and the pointer isn't freed indeed. It is just a false negative in kmemleak and it would appear as a leak at some point. But the previous patch (do_tty_hangup) seems to fix one of the leaks.
For the 2nd leak, proc_set_tty is called and, for symmetry, I added put_pid in proc_clear_tty (but without any deep thought). I also haven't checked any lockdep issues with adding put_pid when p->sighand->siglock is held.
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