From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dave Jones , Sasha Levin , Ming Lei Subject: [ 09/68] sysfs: fix race between readdir and lseek Date: Tue, 2 Apr 2013 15:12:58 -0700 Message-Id: <20130402221330.995733177@linuxfoundation.org> In-Reply-To: <20130402221329.915209206@linuxfoundation.org> References: <20130402221329.915209206@linuxfoundation.org> List-ID: 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ming Lei commit 991f76f837bf22c5bb07261cfd86525a0a96650c upstream. While readdir() is running, lseek() may set filp->f_pos as zero, then may leave filp->private_data pointing to one sysfs_dirent object without holding its reference counter, so the sysfs_dirent object may be used after free in next readdir(). This patch holds inode->i_mutex to avoid the problem since the lock is always held in readdir path. Reported-by: Dave Jones Tested-by: Sasha Levin Signed-off-by: Ming Lei Signed-off-by: Greg Kroah-Hartman --- fs/sysfs/dir.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -1040,10 +1040,21 @@ static int sysfs_readdir(struct file * f return 0; } +static loff_t sysfs_dir_llseek(struct file *file, loff_t offset, int whence) +{ + struct inode *inode = file->f_path.dentry->d_inode; + loff_t ret; + + mutex_lock(&inode->i_mutex); + ret = generic_file_llseek(file, offset, whence); + mutex_unlock(&inode->i_mutex); + + return ret; +} const struct file_operations sysfs_dir_operations = { .read = generic_read_dir, .readdir = sysfs_readdir, .release = sysfs_dir_release, - .llseek = generic_file_llseek, + .llseek = sysfs_dir_llseek, };