From 1af95de6f0119d5bde02d3a811a9f3a3661e954e Mon Sep 17 00:00:00 2001
From: Wang YanQing <udknight@gmail.com>
Date: Tue, 23 Jun 2015 18:54:45 +0800
Subject: [PATCH] fs:super:get_anon_bdev: fix race condition could cause dev
exceed its upper limitation
Execution of get_anon_bdev concurrently and preemptive kernel all
could bring race condition, it isn't enough to check dev against
its upper limitation with equality operator only.
This patch fix it.
Signed-off-by: Wang YanQing <udknight@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/super.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/super.c b/fs/super.c
index 928c20f47af9..b61372354f2b 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -842,7 +842,7 @@ int get_anon_bdev(dev_t *p)
else if (error)
return -EAGAIN;
- if (dev == (1 << MINORBITS)) {
+ if (dev >= (1 << MINORBITS)) {
spin_lock(&unnamed_dev_lock);
ida_remove(&unnamed_dev_ida, dev);
if (unnamed_dev_start > dev)
--
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