Re: [RESEND 1/1] Bluetooth: Use chan_list_lock to protect the whole put/destroy invokation

From: Lee Jones
Date: Fri Jul 15 2022 - 03:28:51 EST


> Hi Lee,
> > > > > > I'm struggling to apply this for test:
> > > > > >
> > > > > > "error: corrupt patch at line 6"
> > > > >
> > > > > Check with the attached patch.
> > > >
> > > > With the patch applied:
> > > >
> > > > [ 188.825418][ T75] refcount_t: addition on 0; use-after-free.
> > > > [ 188.825418][ T75] refcount_t: addition on 0; use-after-free.
> > >
> > > Looks like the changes just make the issue more visible since we are
> > > trying to add a refcount when it is already 0 so this proves the
> > > design is not quite right since it is removing the object from the
> > > list only when destroying it while we probably need to do it before.
> > >
> > > How about we use kref_get_unless_zero as it appears it was introduced
> > > exactly for such cases (patch attached.)
> >
> > Looks like I missed a few places like l2cap_global_chan_by_psm so here
> > is another version.
>
> Any feedback regarding these changes?

Not yet. I'll have time to test this next week.

Things really stacked up this week, apologies.

--
Lee Jones [李琼斯]
Principal Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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