Prev: linux-next: manual merge of the v4l-dvb tree
Next: linux-next: manual merge of the kvm tree with Linus' tree
From: Andrew Morton on 12 May 2010 23:20
On Wed, 12 May 2010 12:08:00 -0400 Eric Paris <eparis(a)redhat.com> wrote:

> From: root <root(a)tyan-gt24-04.rhts.eng.bos.redhat.com>

hm.

> There is a race in the inotify add/rm watch code. A task can find and
> remove a mark which doesn't have all of it's references. This can
> result in a use after free/double free situation.
>
> Task A Task B
> ------------ -----------
> inotify_new_watch()
> allocate a mark (refcnt == 1)
> add it to the idr
> inotify_rm_watch()
> inotify_remove_from_idr()
> fsnotify_put_mark()
> refcnt hits 0, free
> take reference because we are on idr
> [at this point it is a use after free]
> [time goes on]
> refcnt may hit 0 again, double free
>
> The fix is to take the reference BEFORE the object can be found in the
> idr.
>
> Signed-off-by: Eric Paris <eparis(a)redhat.com>

The changelog has no "Cc: <stable(a)kernel.org>". I suspect it should
have that?

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo(a)vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
From: Eric Paris on 13 May 2010 07:40
On Wed, 2010-05-12 at 20:16 -0400, Andrew Morton wrote:
> On Wed, 12 May 2010 12:08:00 -0400 Eric Paris <eparis(a)redhat.com> wrote:
>
> > From: root <root(a)tyan-gt24-04.rhts.eng.bos.redhat.com>
>
> hm.

Well poop. That's what I get for using git on a random test box. I
moved it to my real tree with git-format-patch > git-am. I'll fix the
author.

> > There is a race in the inotify add/rm watch code. A task can find and
> > remove a mark which doesn't have all of it's references. This can
> > result in a use after free/double free situation.
> >
> > Task A Task B
> > ------------ -----------
> > inotify_new_watch()
> > allocate a mark (refcnt == 1)
> > add it to the idr
> > inotify_rm_watch()
> > inotify_remove_from_idr()
> > fsnotify_put_mark()
> > refcnt hits 0, free
> > take reference because we are on idr
> > [at this point it is a use after free]
> > [time goes on]
> > refcnt may hit 0 again, double free
> >
> > The fix is to take the reference BEFORE the object can be found in the
> > idr.
> >
> > Signed-off-by: Eric Paris <eparis(a)redhat.com>
>
> The changelog has no "Cc: <stable(a)kernel.org>". I suspect it should
> have that?

Will fix before I ask Linus to pull....

-Eric

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo(a)vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
 | 
Pages: 1
Prev: linux-next: manual merge of the v4l-dvb tree
Next: linux-next: manual merge of the kvm tree with Linus' tree