Commit c3cee372 authored by Alexander Potapenko's avatar Alexander Potapenko Committed by Linus Torvalds

kasan: avoid overflowing quarantine size on low memory systems

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.

[ cleanup: use WARN_ONCE return value]
Fixes: 55834c59 ("mm: kasan: initial memory quarantine implementation")
Signed-off-by: default avatarAlexander Potapenko <>
Reported-by: default avatarDmitry Vyukov <>
Cc: Andrey Ryabinin <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 7e088978
......@@ -198,7 +198,7 @@ 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;
......@@ -216,7 +216,12 @@ void quarantine_reduce(void)
new_quarantine_size = (READ_ONCE(totalram_pages) << PAGE_SHIFT) /
new_quarantine_size -= QUARANTINE_PERCPU_SIZE * num_online_cpus();
percpu_quarantines = QUARANTINE_PERCPU_SIZE * num_online_cpus();
if (WARN_ONCE(new_quarantine_size < percpu_quarantines,
"Too little memory, disabling global KASAN quarantine.\n"))
new_quarantine_size = 0;
new_quarantine_size -= percpu_quarantines;
WRITE_ONCE(quarantine_size, new_quarantine_size);
last = global_quarantine.head;
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