From 453745fbbebecf7e459785db7e29e11563908525 Mon Sep 17 00:00:00 2001
From: Coly Li <colyli@suse.de>
Date: Sat, 9 Feb 2019 12:53:08 +0800
Subject: [PATCH] bcache: fix input overflow to journal_delay_ms
Git-commit: 453745fbbebecf7e459785db7e29e11563908525
Patch-mainline: v5.1-rc1
References: bsc#1130972

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>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

---
 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 d292eb757ac4..201e85bbe3eb 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -821,7 +821,9 @@ 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