From: Ming Lei Date: Wed, 20 Mar 2013 15:25:24 +0000 (+0800) Subject: sysfs: fix race between readdir and lseek X-Git-Tag: v3.8.6~116 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=9e14083e68a88bc48631d59a3bbdf4a800c1646c;p=karo-tx-linux.git sysfs: fix race between readdir and lseek 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 --- diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index 2fbdff6be25c..28795fea0c6a 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, };