The patch titled
Subject: kasan: avoid overflowing quarantine size on low memory systems
has been added to the -mm tree. Its filename is
kasan-avoid-overflowing-quarantine-size-on-low-memory-systems.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kasan-avoid-overflowing-quarantine-size-on-low-memory-systems.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kasan-avoid-overflowing-quarantine-size-on-low-memory-systems.patch
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------------------------------------------------------
From: Alexander Potapenko <glider@xxxxxxxxxx>
Subject: 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.
Link: http://lkml.kernel.org/r/1470063563-96266-1-git-send-email-glider@xxxxxxxxxx
Fixes: 55834c59098d ("mm: kasan: initial memory quarantine implementation")
Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/kasan/quarantine.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff -puN mm/kasan/quarantine.c~kasan-avoid-overflowing-quarantine-size-on-low-memory-systems mm/kasan/quarantine.c
--- a/mm/kasan/quarantine.c~kasan-avoid-overflowing-quarantine-size-on-low-memory-systems
+++ a/mm/kasan/quarantine.c
@@ -198,7 +198,7 @@ void quarantine_put(struct kasan_free_me
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 +216,15 @@ 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;
_
Patches currently in -mm which might be from glider@xxxxxxxxxx are
kasan-avoid-overflowing-quarantine-size-on-low-memory-systems.patch
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