linux-kernel - [PATCH V2] Fix handling of parse errors in sysfs

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Date:	Wed,  5 Jan 2011 13:16:33 -0700
From:	Eric B Munson <emunson@...bm.net>
To:	akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org, mel@....ul.ie,
	caiqian@...hat.com, mhocko@...e.cz,
	Eric B Munson <emunson@...bm.net>, stable@...nel.org
Subject: [PATCH V2] Fix handling of parse errors in sysfs

When parsing changes to the huge page pool sizes made from userspace
via the sysfs interface, bogus input values are being covered up
by nr_hugepages_store_common and nr_overcommit_hugepages_store
returning 0 when strict_strtoul returns an error.  This can cause an
infinite loop in the nr_hugepages_store code.  This patch changes
the return value for these functions to -EINVAL when strict_strtoul
returns an error.

Reported-by: CAI Qian <caiqian@...hat.com>

Signed-off-by: Eric B Munson <emunson@...bm.net>
Cc: stable@...nel.org
---
Changes from V1
 Reword leader to show problem that is fixed by the patch
 Add stable@...nel.org as a CC to handle stable submission the right way

 mm/hugetlb.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 8585524..5cb71a9 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1440,7 +1440,7 @@ static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
 
 	err = strict_strtoul(buf, 10, &count);
 	if (err)
-		return 0;
+		return -EINVAL;
 
 	h = kobj_to_hstate(kobj, &nid);
 	if (nid == NUMA_NO_NODE) {
@@ -1519,7 +1519,7 @@ static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
 
 	err = strict_strtoul(buf, 10, &input);
 	if (err)
-		return 0;
+		return -EINVAL;
 
 	spin_lock(&hugetlb_lock);
 	h->nr_overcommit_huge_pages = input;
-- 
1.7.1

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