From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx201.postini.com [74.125.245.201]) by kanga.kvack.org (Postfix) with SMTP id 7FA5E6B0197 for ; Sun, 5 May 2013 11:44:31 -0400 (EDT) Received: by mail-da0-f51.google.com with SMTP id h15so1416029dan.24 for ; Sun, 05 May 2013 08:44:30 -0700 (PDT) From: Sha Zhengju Subject: [PATCH 2/3] memcg: check more strictly to avoid PAGE_ALIGN wrapped to 0 Date: Sun, 5 May 2013 23:43:10 +0800 Message-Id: <1367768590-4403-1-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: nishimura@mxp.nes.nec.co.jp, akpm@linux-foundation.org, mhocko@suse.cz, jeff.liu@oracle.com, Sha Zhengju Since PAGE_ALIGN is aligning up(the next page boundary), this can prevent input values wrapped to 0 and cause strange result to user. This patch also rename the second arg of res_counter_memparse_write_strategy() to 'resp' and add a local variable 'res' to save the too often dereferences. Thanks Andrew for pointing it out! Signed-off-by: Sha Zhengju Reported-by: Li Wenpeng --- kernel/res_counter.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/kernel/res_counter.c b/kernel/res_counter.c index 3f0417f..be8ddda 100644 --- a/kernel/res_counter.c +++ b/kernel/res_counter.c @@ -178,23 +178,29 @@ u64 res_counter_read_u64(struct res_counter *counter, int member) #endif int res_counter_memparse_write_strategy(const char *buf, - unsigned long long *res) + unsigned long long *resp) { char *end; + unsigned long long res; /* return RES_COUNTER_MAX(unlimited) if "-1" is specified */ if (*buf == '-') { - *res = simple_strtoull(buf + 1, &end, 10); - if (*res != 1 || *end != '\0') + res = simple_strtoull(buf + 1, &end, 10); + if (res != 1 || *end != '\0') return -EINVAL; - *res = RES_COUNTER_MAX; + *resp = RES_COUNTER_MAX; return 0; } - *res = memparse(buf, &end); + res = memparse(buf, &end); if (*end != '\0') return -EINVAL; - *res = PAGE_ALIGN(*res); + if (PAGE_ALIGN(res) >= res) + res = PAGE_ALIGN(res); + else + res = RES_COUNTER_MAX; /* avoid PAGE_ALIGN wrapping to zero */ + + *resp = 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