Re: [PATCH] rpmsg: glink: Remove channel decouple from rpdev release

[Chris Lew]

On 10/9/2019 10:04 PM, Stephen Boyd wrote:
> Quoting Chris Lew (2019-10-08 18:33:45)
> > If a channel is being rapidly restarted and the kobj release worker is
> > busy, there is a chance the the rpdev_release function will run after
> > the channel struct itself has been released.
> >
> > There should not be a need to decouple the channel from rpdev in the
> > rpdev release since that should only happen from the channel close
> > commands.
> >
> > Signed-off-by: Chris Lew <clew@xxxxxxxxxxxxxx>
>
> Fixes tag? The whole thing sounds broken and probably is still racy in
> the face of SMP given that channel->rpdev is tested for "published" or
> not. Can you describe the race that you're closing more?

Thanks Stephen, will add Fixes tag and try to describe the race better.

I agree that the whole thing sounds broken, the glink channel cleanup 
code has a couple bugs that need to be addressed in a more extensive 
patch. This patch is more to address the immediate issue of a 
use-after-free from one of the races.

--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project