From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx180.postini.com [74.125.245.180]) by kanga.kvack.org (Postfix) with SMTP id 8FC426B0005 for ; Fri, 12 Apr 2013 02:39:45 -0400 (EDT) Received: by mail-pb0-f41.google.com with SMTP id mc17so1263676pbc.14 for ; Thu, 11 Apr 2013 23:39:44 -0700 (PDT) From: Sha Zhengju Subject: [PATCH] memcg: Check more strictly to avoid ULLONG overflow by PAGE_ALIGN Date: Fri, 12 Apr 2013 14:39:23 +0800 Message-Id: <1365748763-4350-1-git-send-email-handai.szj@taobao.com> Sender: owner-linux-mm@kvack.org List-ID: To: cgroups@vger.kernel.org, linux-mm@kvack.org Cc: akpm@linux-foundation.org, jeff.liu@oracle.com, Sha Zhengju From: Sha Zhengju While writing memory.limit_in_bytes, a confusing result may happen: $ mkdir /memcg/test $ cat /memcg/test/memory.limit_in_bytes 9223372036854775807 $ cat /memcg/test/memory.memsw.limit_in_bytes 9223372036854775807 $ echo 18446744073709551614 > /memcg/test/memory.limit_in_bytes $ cat /memcg/test/memory.limit_in_bytes 0 Strangely, the write successed and reset the limit to 0. The patch corrects RESOURCE_MAX and fixes this kind of overflow. Signed-off-by: Sha Zhengju Reported-by: Li Wenpeng < xingke.lwp@taobao.com> Cc: Jie Liu --- include/linux/res_counter.h | 2 +- kernel/res_counter.c | 8 +++++++- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h index c230994..c2f01fc 100644 --- a/include/linux/res_counter.h +++ b/include/linux/res_counter.h @@ -54,7 +54,7 @@ struct res_counter { struct res_counter *parent; }; -#define RESOURCE_MAX (unsigned long long)LLONG_MAX +#define RESOURCE_MAX (unsigned long long)ULLONG_MAX /** * Helpers to interact with userspace diff --git a/kernel/res_counter.c b/kernel/res_counter.c index ff55247..6c35310 100644 --- a/kernel/res_counter.c +++ b/kernel/res_counter.c @@ -195,6 +195,12 @@ int res_counter_memparse_write_strategy(const char *buf, if (*end != '\0') return -EINVAL; - *res = PAGE_ALIGN(*res); + /* Since PAGE_ALIGN is aligning up(the next page boundary), + * check the left space to avoid overflow to 0. */ + if (RESOURCE_MAX - *res < PAGE_SIZE - 1) + *res = RESOURCE_MAX; + else + *res = PAGE_ALIGN(*res); + return 0; } -- 1.7.9.5 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org