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.
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Fixes: 55834c59098d ("mm: kasan: initial memory quarantine
implementation")
Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
---
mm/kasan/quarantine.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
index 65793f1..416d3b0 100644
--- 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 +214,15 @@ 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();
+ if (new_quarantine_size < percpu_quarantines) {
+ WARN_ONCE(1,
+ "Too little memory, disabling global KASAN quarantine.\n",
+ );
+ new_quarantine_size = 0;
+ } else {
+ new_quarantine_size -= percpu_quarantines;
+ }
WRITE_ONCE(quarantine_size, new_quarantine_size);
last = global_quarantine.head;
--
2.8.0.rc3.226.g39d4020
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