for-next/sysfs-fix/0009-bcache-fix-input-overflow-to-journal_delay_ms.patch

From ddf36f1532d71eb39fc59cd4656201ba55061bdf Mon Sep 17 00:00:00 2001
From: Coly Li <colyli@suse.de>
Date: Thu, 20 Dec 2018 21:30:56 +0800
Subject: [PATCH 09/11] bcache: fix input overflow to journal_delay_ms

c->journal_delay_ms is in type unsigned short, it is set via sysfs
interface and converted by sysfs_strtoul() from input string to
unsigned short value. Therefore overflow to unsigned short might be
happen when the converted value exceed USHRT_MAX. e.g. writing
65536 into sysfs file journal_delay_ms, c->journal_delay_ms is set to
0.

This patch uses sysfs_strtoul_clamp() to convert the input string and
limit value range in [0, USHRT_MAX], to avoid the input overflow.

Signed-off-by: Coly Li <colyli@suse.de>
---
 drivers/md/bcache/sysfs.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index aacb0e2fc81c..db12d4210a20 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -809,7 +809,9 @@ STORE(__bch_cache_set)
 		}
 	}
 
-	sysfs_strtoul(journal_delay_ms,		c->journal_delay_ms);
+	sysfs_strtoul_clamp(journal_delay_ms,
+			    c->journal_delay_ms,
+			    0, USHRT_MAX);
 	sysfs_strtoul_bool(verify,		c->verify);
 	sysfs_strtoul_bool(key_merging_disabled,c->key_merging_disabled);
 	sysfs_strtoul(expensive_debug_checks,	c->expensive_debug_checks);
-- 
2.16.4