sysfs: fix race between readdir and lseek
authorMing Lei <ming.lei@canonical.com>
Wed, 20 Mar 2013 15:25:24 +0000 (23:25 +0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 20 Mar 2013 23:53:42 +0000 (16:53 -0700)
commit991f76f837bf22c5bb07261cfd86525a0a96650c
treeaabd6397c35daee20d579507f4c5256e88e813ec
parenta937536b868b8369b98967929045f1df54234323
sysfs: fix race between readdir and lseek

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>
fs/sysfs/dir.c