lkml.org 
[lkml]   [2019]   [Apr]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2] Input: uinput: Avoid Object-Already-Free with a global lock
On Tue, Apr 23, 2019 at 08:49:44AM +0000, dmitry.torokhov@gmail.com wrote:
> On Tue, Apr 23, 2019 at 12:51:13PM +0530, Mukesh Ojha wrote:

> > I have taken care this case from ioctl and release point of view.
> >
> > Even if the release gets called first it will make the
> > file->private_data=NULL.
> > and further call to ioctl will not be a problem as the check is already
> > there.
>
> Al, do we have any protections in VFS layer from userspace hanging onto
> a file descriptor and calling ioctl() on it even as another thread
> calls close() on the same fd?
>
> Should the issue be solved by individual drivers, or more careful
> accounting for currently running operations is needed at VFS layer?

Neither. An overlap of ->release() and ->ioctl() is possible only
if you've got memory corruption somewhere.

close() overlapping ioctl() is certainly possible, and won't trigger
that at all - sys_ioctl() holds onto reference to struct file, so
its refcount won't reach zero until we are done with it.

\
 
 \ /
  Last update: 2019-04-23 13:06    [W:0.124 / U:4.860 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site