From: Andrew Morton <akpm@linux-foundation.org>
To: Alexander Potapenko <glider@google.com>
Cc: dvyukov@google.com, kcc@google.com, aryabinin@virtuozzo.com,
adech.fo@gmail.com, cl@linux.com, rostedt@goodmis.org,
js1304@gmail.com, iamjoonsoo.kim@lge.com,
kuthonuzo.luruo@hpe.com, kasan-dev@googlegroups.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] kasan: avoid overflowing quarantine size on low memory systems
Date: Mon, 1 Aug 2016 13:30:10 -0700 [thread overview]
Message-ID: <20160801133010.08b1733dc7f62fe68713c0ba@linux-foundation.org> (raw)
In-Reply-To: <1470063563-96266-1-git-send-email-glider@google.com>
On Mon, 1 Aug 2016 16:59:23 +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
> @@ -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;
This is a little tidier:
--- a/mm/kasan/quarantine.c~kasan-avoid-overflowing-quarantine-size-on-low-memory-systems-fix
+++ a/mm/kasan/quarantine.c
@@ -217,14 +217,11 @@ void quarantine_reduce(void)
new_quarantine_size = (READ_ONCE(totalram_pages) << PAGE_SHIFT) /
QUARANTINE_FRACTION;
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",
- );
+ if (WARN_ONCE(new_quarantine_size < percpu_quarantines,
+ "Too little memory, disabling global KASAN quarantine.\n"))
new_quarantine_size = 0;
- } else {
+ else
new_quarantine_size -= percpu_quarantines;
- }
WRITE_ONCE(quarantine_size, new_quarantine_size);
last = global_quarantine.head;
_
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next prev parent reply other threads:[~2016-08-01 20:30 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-01 14:59 [PATCH] kasan: avoid overflowing quarantine size on low memory systems Alexander Potapenko
2016-08-01 20:30 ` Andrew Morton [this message]
2016-08-02 10:00 ` Andrey Ryabinin
2016-08-02 10:05 ` Dmitry Vyukov
2016-08-02 10:07 ` Alexander Potapenko
2016-08-02 10:15 ` Dmitry Vyukov
2016-08-02 10:23 ` Andrey Ryabinin
2016-08-02 10:27 ` Alexander Potapenko
2016-08-02 10:05 ` Alexander Potapenko
2016-08-31 2:39 ` amanda4ray
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