Messages in this thread | | | Date | Wed, 10 Aug 2016 15:50:15 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH v2] kasan: avoid overflowing quarantine size on low memory systems |
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On Tue, 2 Aug 2016 12:27:00 +0200 Alexander Potapenko <glider@google.com> wrote:
> If the total amount of memory assigned to quarantine is less than the > amount of memory assigned to per-cpu quarantines, |new_quarantine_size| > may overflow. Instead, set it to zero. > > ... > > --- a/mm/kasan/quarantine.c > +++ b/mm/kasan/quarantine.c > @@ -196,7 +196,7 @@ void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache) > > void quarantine_reduce(void) > { > - size_t new_quarantine_size; > + size_t new_quarantine_size, percpu_quarantines; > unsigned long flags; > struct qlist_head to_free = QLIST_INIT; > size_t size_to_free = 0; > @@ -214,7 +214,9 @@ void quarantine_reduce(void) > */ > new_quarantine_size = (READ_ONCE(totalram_pages) << PAGE_SHIFT) / > QUARANTINE_FRACTION; > - new_quarantine_size -= QUARANTINE_PERCPU_SIZE * num_online_cpus(); > + percpu_quarantines = QUARANTINE_PERCPU_SIZE * num_online_cpus(); > + new_quarantine_size = (new_quarantine_size < percpu_quarantines) ? > + 0 : new_quarantine_size - percpu_quarantines; > WRITE_ONCE(quarantine_size, new_quarantine_size); > > last = global_quarantine.head;
Confused. Which kernel version is this supposed to apply to?
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