Messages in this thread | | | Date | Wed, 30 Jun 2021 17:10:36 +0100 | From | Mark Brown <> | Subject | Re: [PATCH] cgroup1: fix leaked context root causing sporadic NULL deref in LTP |
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On Wed, Jun 16, 2021 at 11:23:34AM -0400, Tejun Heo wrote: > On Wed, Jun 16, 2021 at 08:51:57AM -0400, Paul Gortmaker wrote:
> > A fix would be to not leave the stale reference in fc->root as follows:
> > -------------- > > dput(fc->root); > > + fc->root = NULL; > > deactivate_locked_super(sb); > > --------------
> > ...but then we are just open-coding a duplicate of fc_drop_locked() so we > > simply use that instead.
> As this is unlikely to be a real-world problem both in probability and > circumstances, I'm applying this to cgroup/for-5.14 instead of > cgroup/for-5.13-fixes.
FWIW at Arm we've started seeing what appears to be this issue blow up very frequently in some of our internal LTP CI runs against -next, seems to be mostly on lower end platforms. We seem to have started finding it at roughly the same time that the Yocto people did, I guess some other change made it more likely to trigger. Not exactly real world usage obviously but it's creating quite a bit of noise in testing which is disruptive so it'd be good to get it into -next as a fix. [unhandled content-type:application/pgp-signature] | |