Messages in this thread | | | Date | Fri, 29 Aug 2014 20:57:18 +0300 | From | Andreea Bernat <> | Subject | Re: [PATCH RFC] rcu: assoc_array: Add critical section to avoid a bug |
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On Thu, Aug 28, 2014 at 12:32:31PM +0100, David Howells wrote: > Andreea-Cristina Bernat <bernat.ada@gmail.com> wrote: > > > * The function "assoc_array_gc()" could be preempted between the call to > > "assoc_array_apply_edit()" call and the assignment > > "edit->array->nr_leaves_on_tree = nr_leaves_on_tree;", so the grace > > period could complete. > > The bug is real, but this patch isn't the right solution. > > The edit script should be considered inaccessible to a function the moment it > calls assoc_array_apply_edit() or assoc_array_cancel_edit(). I think this is > a better way. > > David > --- > assoc_array.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > commit 10c26fcc224c0515e15272515e7b9006cb08adc8 > Author: David Howells <dhowells@redhat.com> > Date: Wed Aug 27 18:39:44 2014 +0100 > > KEYS: Fix use-after-free in assoc_array_gc() > > An edit script should be considered inaccessible by a function once it has > called assoc_array_apply_edit() or assoc_array_cancel_edit(). > > However, assoc_array_gc() is accessing the edit script just after the > gc_complete: label. > > Reported-by: Andreea-Cristina Bernat <bernat.ada@gmail.com> > Signed-off-by: David Howells <dhowells@redhat.com> > > diff --git a/lib/assoc_array.c b/lib/assoc_array.c > index c0b1007011e1..ae146f0734eb 100644 > --- a/lib/assoc_array.c > +++ b/lib/assoc_array.c > @@ -1735,7 +1735,7 @@ ascend_old_tree: > gc_complete: > edit->set[0].to = new_root; > assoc_array_apply_edit(edit); > - edit->array->nr_leaves_on_tree = nr_leaves_on_tree; > + array->nr_leaves_on_tree = nr_leaves_on_tree; > return 0;
Looks good to me.
Regards, Andreea
> > enomem:
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