tree 5385cf0537e4cad0a2896070c45f2b492a74f0ff
parent 0f8b1a0204a12441cddbbf5be31e6338e0b8da1c
author Ming Lei <ming.lei@canonical.com> 1364868746 +0800
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1365012542 -0700

sysfs: fix use after free in case of concurrent read/write and readdir

The inode->i_mutex isn't hold when updating filp->f_pos
in read()/write(), so the filp->f_pos might be read as
0 or 1 in readdir() when there is concurrent read()/write()
on this same file, then may cause use after free in readdir().

The bug can be reproduced with Li Zefan's test code on the
link:

	https://patchwork.kernel.org/patch/2160771/

This patch fixes the use after free under this situation.

Cc: stable <stable@vger.kernel.org>
Reported-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>