Commit e5110f41 authored Mar 20, 2013 by Ming Lei Committed by Greg Kroah-Hartman Mar 20, 2013

sysfs: handle failure path correctly for readdir()



In case of 'if (filp->f_pos ==  0 or 1)' of sysfs_readdir(),
the failure from filldir() isn't handled, and the reference counter
of the sysfs_dirent object pointed by filp->private_data will be
released without clearing filp->private_data, so use after free
bug will be triggered later.

This patch returns immeadiately under the situation for fixing the bug,
and it is reasonable to return from readdir() when filldir() fails.

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>

parent 991f76f8

fs/sysfs/dir.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -1020,6 +1020,8 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
		ino = parent_sd->s_ino;
		if (filldir(dirent, ".", 1, filp->f_pos, ino, DT_DIR) == 0)
		filp->f_pos++;
		else
		return 0;
		}
		if (filp->f_pos == 1) {
		if (parent_sd->s_parent)
		@@ -1028,6 +1030,8 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
		ino = parent_sd->s_ino;
		if (filldir(dirent, "..", 2, filp->f_pos, ino, DT_DIR) == 0)
		filp->f_pos++;
		else
		return 0;
		}
		mutex_lock(&sysfs_mutex);
		for (pos = sysfs_dir_pos(ns, parent_sd, filp->f_pos, pos);