linux-kernel - [PATCH][securityfs][2.6.34] Drop dentry reference count when mknod fails

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Message-ID: <201007151325.06942.tvrtko.ursulin@sophos.com>
Date:	Thu, 15 Jul 2010 13:25:06 +0100
From:	Tvrtko Ursulin <tvrtko.ursulin@...hos.com>
To:	James Morris <jmorris@...ei.org>
CC:	"greg@...ah.com" <greg@...ah.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	<linux-security-module@...r.kernel.org>
Subject: [PATCH][securityfs][2.6.34] Drop dentry reference count when mknod fails


lookup_one_len increments dentry reference count which is not decremented
when the create operation fails. This can cause a kernel BUG at
fs/dcache.c:676 at unmount time. Also error code returned when new_inode()
fails was replaced with more appropriate -ENOMEM.


Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@...hos.com>
---
 inode.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff -upr linux-2.6.34/security/inode.c linux-2.6.34-new/security/inode.c
--- linux-2.6.34/security/inode.c       2010-05-16 22:17:36.000000000 +0100
+++ linux-2.6.34-new/security/inode.c   2010-07-15 13:20:38.133783253 +0100
@@ -86,7 +86,7 @@ static int mknod(struct inode *dir, stru
                         int mode, dev_t dev)
 {
        struct inode *inode;
-       int error = -EPERM;
+       int error = -ENOMEM;

        if (dentry->d_inode)
                return -EEXIST;
@@ -166,6 +166,8 @@ static int create_by_name(const char *na
                        error = mkdir(parent->d_inode, *dentry, mode);
                else
                        error = create(parent->d_inode, *dentry, mode);
+               if (error)
+                       dput(dentry);
        } else
                error = PTR_ERR(*dentry);
        mutex_unlock(&parent->d_inode->i_mutex);



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