From: Ben Hutchings <ben@decadent.org.uk>
Date: Mon, 16 Feb 2015 03:21:17 +0000 (+0000)
Subject: vfs: Fix vfsmount_lock imbalance in path_init()
X-Git-Tag: v3.2.67~6
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=d8c8133eb0460a183e69cf8a5d722688916960de

vfs: Fix vfsmount_lock imbalance in path_init()

When backporting commit 4023bfc9f351 ("be careful with nd->inode in
path_init() and follow_dotdot_rcu()"), I failed to account for the
vfsmount_lock that is used in 3.2 but not upstream.  path_init() takes
the lock if performing RCU lookup, but must drop it if (and only if)
it subsequently fails.

Reported-by: nuxi@vault24.org
References: https://bugzilla.kernel.org/show_bug.cgi?id=92531
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Tested-by: nuxi@vault24.org
---

diff --git a/fs/namei.c b/fs/namei.c
index dea2dabc62c1..c8b13a92bf69 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1567,6 +1567,7 @@ static int path_init(int dfd, const char *name, unsigned int flags,
 	if (!(nd->flags & LOOKUP_ROOT))
 		nd->root.mnt = NULL;
 	rcu_read_unlock();
+	br_read_unlock(vfsmount_lock);
 	return -ECHILD;
 
 fput_fail: