| From | Luis Henriques <> | Subject | [PATCH 056/102] sysfs: fix race between readdir and lseek | Date | Mon, 8 Apr 2013 10:50:11 +0100 |
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3.5.7.10 -stable review patch. If anyone has any objections, please let me know.
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From: Ming Lei <ming.lei@canonical.com>
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 <davej@redhat.com> Tested-by: Sasha Levin <levinsasha928@gmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [ luis: backported to 3.5: removed usage of file_inode() ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- 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 2ee0864..8777436 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -1063,10 +1063,21 @@ 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, }; -- 1.8.1.2
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