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SubjectRe: [PATCH v3] kasan/quarantine: fix bugs on qlist_move_cache()
On Fri, Jul 01, 2016 at 05:17:10PM +0300, Andrey Ryabinin wrote:
>
>
> On 07/01/2016 05:02 PM, js1304@gmail.com wrote:
> > From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> >
> > There are two bugs on qlist_move_cache(). One is that qlist's tail
> > isn't set properly. curr->next can be NULL since it is singly linked
> > list and NULL value on tail is invalid if there is one item on qlist.
> > Another one is that if cache is matched, qlist_put() is called and
> > it will set curr->next to NULL. It would cause to stop the loop
> > prematurely.
> >
> > These problems come from complicated implementation so I'd like to
> > re-implement it completely. Implementation in this patch is really
> > simple. Iterate all qlist_nodes and put them to appropriate list.
> >
> > Unfortunately, I got this bug sometime ago and lose oops message.
> > But, the bug looks trivial and no need to attach oops.
> >
> > v3: fix build warning
> >
> > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> > ---
> > mm/kasan/quarantine.c | 21 +++++++--------------
> > 1 file changed, 7 insertions(+), 14 deletions(-)
> >
> > diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
> > index 4973505..cf92494 100644
> > --- a/mm/kasan/quarantine.c
> > +++ b/mm/kasan/quarantine.c
> > @@ -238,30 +238,23 @@ static void qlist_move_cache(struct qlist_head *from,
> > struct qlist_head *to,
> > struct kmem_cache *cache)
> > {
> > - struct qlist_node *prev = NULL, *curr;
> > + struct qlist_node *curr;
> >
> > if (unlikely(qlist_empty(from)))
> > return;
> >
> > curr = from->head;
> > + qlist_init(from);
> > while (curr) {
> > struct qlist_node *qlink = curr;
>
> Can you please also get rid of either qlink or curr.
> Those are essentially the same pointers.

Hello,

Before putting the qlist_node to the list, we need to calculate
curr->next and remember it to iterate the list. I use curr
for this purpose so qlink and curr are not the same pointer.

Thanks.

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