This is a note to let you know that I've just added the patch titled
kasan: avoid overflowing quarantine size on low memory systems
to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kasan-avoid-overflowing-quarantine-size-on-low-memory-systems.patch
and it can be found in the queue-4.7 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From c3cee372282cb6bcdf19ac1457581d5dd5ecb554 Mon Sep 17 00:00:00 2001
From: Alexander Potapenko <glider@xxxxxxxxxx>
Date: Tue, 2 Aug 2016 14:02:58 -0700
Subject: kasan: avoid overflowing quarantine size on low memory systems
From: Alexander Potapenko <glider@xxxxxxxxxx>
commit c3cee372282cb6bcdf19ac1457581d5dd5ecb554 upstream.
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.
[akpm@xxxxxxxxxxxxxxxxxxxx: cleanup: use WARN_ONCE return value]
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>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/kasan/quarantine.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
--- a/mm/kasan/quarantine.c
+++ b/mm/kasan/quarantine.c
@@ -196,7 +196,7 @@ 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;
@@ -214,7 +214,12 @@ 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 (WARN_ONCE(new_quarantine_size < percpu_quarantines,
+ "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 stable-queue which might be from glider@xxxxxxxxxx are
queue-4.7/mm-kasan-don-t-reduce-quarantine-in-atomic-contexts.patch
queue-4.7/kasan-avoid-overflowing-quarantine-size-on-low-memory-systems.patch
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