From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Message-Id: <20130411202559.162210855@goodmis.org> Date: Thu, 11 Apr 2013 16:26:22 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Dave Jones , Sasha Levin , Ming Lei , Greg Kroah-Hartman Subject: [ 079/171 ] sysfs: fix race between readdir and lseek References: <20130411202503.783159048@goodmis.org> Content-Disposition: inline; filename=0079-sysfs-fix-race-between-readdir-and-lseek.patch List-ID: 3.6.11.2 stable review patch. If anyone has any objections, please let me know. ------------------ From: Ming Lei [ Upstream commit 991f76f837bf22c5bb07261cfd86525a0a96650c ] 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 Cc: Signed-off-by: Ming Lei Signed-off-by: Greg Kroah-Hartman Signed-off-by: Steven Rostedt --- fs/sysfs/dir.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index 2fbdff6..b65a354 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -1058,10 +1058,21 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir) 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, }; -- 1.7.10.4