Messages in this thread Patch in this message | | | Date | Mon, 14 Mar 2022 17:44:29 +0100 | From | Michal Hocko <> | Subject | Re: [PATCH] mm/mempolicy: fix potential mpol_new leak in shared_policy_replace |
| |
On Fri 11-03-22 17:36:24, Miaohe Lin wrote: > If mpol_new is allocated but not used in restart loop, mpol_new will be > freed via mpol_put before returning to the caller. But refcnt is not > initialized yet, so mpol_put could not do the right things and might > leak the unused mpol_new.
The code is really hideous but is there really any bug there? AFAICS the new policy is only allocated in if (n->end > end) branch and that one will set the reference count on the retry. Or am I missing something?
> Fixes: 42288fe366c4 ("mm: mempolicy: Convert shared_policy mutex to spinlock") > Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> > --- > mm/mempolicy.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index 34d2b29c96ad..f19f19d3558b 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -2733,6 +2733,7 @@ static int shared_policy_replace(struct shared_policy *sp, unsigned long start, > mpol_new = kmem_cache_alloc(policy_cache, GFP_KERNEL); > if (!mpol_new) > goto err_out; > + refcount_set(&mpol_new->refcnt, 1); > goto restart; > } > > -- > 2.23.0
-- Michal Hocko SUSE Labs
| |