Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759715AbZLQAyj (ORCPT ); Wed, 16 Dec 2009 19:54:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756036AbZLQAyf (ORCPT ); Wed, 16 Dec 2009 19:54:35 -0500 Received: from kroah.org ([198.145.64.141]:44464 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755641AbZLQAyd (ORCPT ); Wed, 16 Dec 2009 19:54:33 -0500 X-Mailbox-Line: From gregkh@mini.kroah.org Wed Dec 16 16:47:07 2009 Message-Id: <20091217004707.207213364@mini.kroah.org> User-Agent: quilt/0.48-1 Date: Wed, 16 Dec 2009 16:45:53 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Mathieu Desnoyers Subject: [02/18] debugfs: fix create mutex racy fops and private data In-Reply-To: <20091217005306.GA6230@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5548 Lines: 174 2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ From: Mathieu Desnoyers commit d3a3b0adad0865c12e39b712ca89efbd0a3a0dbc upstream. Setting fops and private data outside of the mutex at debugfs file creation introduces a race where the files can be opened with the wrong file operations and private data. It is easy to trigger with a process waiting on file creation notification. Signed-off-by: Mathieu Desnoyers Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- fs/debugfs/inode.c | 55 ++++++++++++++++++++++++++++++----------------------- 1 file changed, 32 insertions(+), 23 deletions(-) --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -32,7 +32,9 @@ static struct vfsmount *debugfs_mount; static int debugfs_mount_count; -static struct inode *debugfs_get_inode(struct super_block *sb, int mode, dev_t dev) +static struct inode *debugfs_get_inode(struct super_block *sb, int mode, dev_t dev, + void *data, const struct file_operations *fops) + { struct inode *inode = new_inode(sb); @@ -47,14 +49,18 @@ static struct inode *debugfs_get_inode(s init_special_inode(inode, mode, dev); break; case S_IFREG: - inode->i_fop = &debugfs_file_operations; + inode->i_fop = fops ? fops : &debugfs_file_operations; + inode->i_private = data; break; case S_IFLNK: inode->i_op = &debugfs_link_operations; + inode->i_fop = fops; + inode->i_private = data; break; case S_IFDIR: inode->i_op = &simple_dir_inode_operations; - inode->i_fop = &simple_dir_operations; + inode->i_fop = fops ? fops : &simple_dir_operations; + inode->i_private = data; /* directory inodes start off with i_nlink == 2 * (for "." entry) */ @@ -67,7 +73,8 @@ static struct inode *debugfs_get_inode(s /* SMP-safe */ static int debugfs_mknod(struct inode *dir, struct dentry *dentry, - int mode, dev_t dev) + int mode, dev_t dev, void *data, + const struct file_operations *fops) { struct inode *inode; int error = -EPERM; @@ -75,7 +82,7 @@ static int debugfs_mknod(struct inode *d if (dentry->d_inode) return -EEXIST; - inode = debugfs_get_inode(dir->i_sb, mode, dev); + inode = debugfs_get_inode(dir->i_sb, mode, dev, data, fops); if (inode) { d_instantiate(dentry, inode); dget(dentry); @@ -84,12 +91,13 @@ static int debugfs_mknod(struct inode *d return error; } -static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) +static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, int mode, + void *data, const struct file_operations *fops) { int res; mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR; - res = debugfs_mknod(dir, dentry, mode, 0); + res = debugfs_mknod(dir, dentry, mode, 0, data, fops); if (!res) { inc_nlink(dir); fsnotify_mkdir(dir, dentry); @@ -97,18 +105,20 @@ static int debugfs_mkdir(struct inode *d return res; } -static int debugfs_link(struct inode *dir, struct dentry *dentry, int mode) +static int debugfs_link(struct inode *dir, struct dentry *dentry, int mode, + void *data, const struct file_operations *fops) { mode = (mode & S_IALLUGO) | S_IFLNK; - return debugfs_mknod(dir, dentry, mode, 0); + return debugfs_mknod(dir, dentry, mode, 0, data, fops); } -static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode) +static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode, + void *data, const struct file_operations *fops) { int res; mode = (mode & S_IALLUGO) | S_IFREG; - res = debugfs_mknod(dir, dentry, mode, 0); + res = debugfs_mknod(dir, dentry, mode, 0, data, fops); if (!res) fsnotify_create(dir, dentry); return res; @@ -142,7 +152,9 @@ static struct file_system_type debug_fs_ static int debugfs_create_by_name(const char *name, mode_t mode, struct dentry *parent, - struct dentry **dentry) + struct dentry **dentry, + void *data, + const struct file_operations *fops) { int error = 0; @@ -167,13 +179,16 @@ static int debugfs_create_by_name(const if (!IS_ERR(*dentry)) { switch (mode & S_IFMT) { case S_IFDIR: - error = debugfs_mkdir(parent->d_inode, *dentry, mode); + error = debugfs_mkdir(parent->d_inode, *dentry, mode, + data, fops); break; case S_IFLNK: - error = debugfs_link(parent->d_inode, *dentry, mode); + error = debugfs_link(parent->d_inode, *dentry, mode, + data, fops); break; default: - error = debugfs_create(parent->d_inode, *dentry, mode); + error = debugfs_create(parent->d_inode, *dentry, mode, + data, fops); break; } dput(*dentry); @@ -224,19 +239,13 @@ struct dentry *debugfs_create_file(const if (error) goto exit; - error = debugfs_create_by_name(name, mode, parent, &dentry); + error = debugfs_create_by_name(name, mode, parent, &dentry, + data, fops); if (error) { dentry = NULL; simple_release_fs(&debugfs_mount, &debugfs_mount_count); goto exit; } - - if (dentry->d_inode) { - if (data) - dentry->d_inode->i_private = data; - if (fops) - dentry->d_inode->i_fop = fops; - } exit: return dentry; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/