Messages in this thread | | | Date | Mon, 12 Nov 2007 16:48:02 -0800 | From | Jeremy Fitzhardinge <> | Subject | Re: mm_release() call in exit_mm() looks dangerous |
| |
Jesper Juhl wrote: > In kernel/exit.c we have this code : > > static void exit_mm(struct task_struct * tsk) > { > struct mm_struct *mm = tsk->mm; > > mm_release(tsk, mm); > if (!mm) > return; > ... > > > But, mm_release() may dereference it's second argument ('mm'), so > shouldn't we be doing the "!mm" test *before* we call mm_release() and > not after? > I don't know the mm code well enough to be able to tell if some of the > other stuff mm_release does needs to be done always and the mm > dereference can't actually happen, but maybe someone else who knows > the code better can tell... In any case, what's currently there looks > a little shaky.. >
Yeah, it looks wrong. mm_release() calls deactivate_mm() as its first act, which could well dereference mm (though it often doesn't).
J - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |