linux-kernel - [PATCH 5/5] mm/backing-dev.c: fix error path in wb

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Date:	Tue,  9 Feb 2016 21:11:16 +0100
From:	Rasmus Villemoes <linux@...musvillemoes.dk>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Michal Hocko <mhocko@...e.com>,
	Vladimir Davydov <vdavydov@...tuozzo.com>,
	"David S. Miller" <davem@...emloft.net>,
	Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: [PATCH 5/5] mm/backing-dev.c: fix error path in wb_init()

We need to use post-decrement to get percpu_counter_destroy() called
on &wb->stat[0]. Moreover, the pre-decremebt would cause infinite
out-of-bounds accesses if the setup code failed at i==0.

Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
---
 mm/backing-dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index cc5d29d2da9b..723f3e624b9a 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -328,7 +328,7 @@ static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
 	return 0;
 
 out_destroy_stat:
-	while (--i)
+	while (i--)
 		percpu_counter_destroy(&wb->stat[i]);
 	fprop_local_destroy_percpu(&wb->completions);
 out_put_cong:
-- 
2.1.4