Re: use after free in sysfs_find_dirent

From: Ming Lei
Date: Tue Mar 19 2013 - 07:54:41 EST

Hi Sasha,

On Tue, Mar 19, 2013 at 11:40 AM, Ming Lei <tom.leiming@xxxxxxxxx> wrote:
> Hi Sasha,
> On Tue, Mar 19, 2013 at 10:06 AM, Sasha Levin <levinsasha928@xxxxxxxxx> wrote:
>> [ 232.822703] sysfs_dir_pos-973 sysfs_dirent use after free: vx855(vx855)-bind, 0-25520352
> Looks filp->f_pos is changed as zero by llseek(), so may leave
> filp->private_data
> point to one refcount-balanced sysfs_dirent object, which will be put
> again afterwards.
> Hope we are luck this time, please try the attachment patch.

Looks the better and simpler way is to hold the i_mutex for llseek.
If you haven't test the v2, please ignore it and just test the attachment
v3 patch.

Ming Lei

Attachment: sysfs-fix-readdir-v3.patch
Description: Binary data