Messages in this thread | | | Date | Wed, 15 Sep 2021 22:42:21 +0000 | From | Jordan Glover <> | Subject | Re: linux 5.14.3: free_user_ns causes NULL pointer dereference |
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On Wednesday, September 15th, 2021 at 9:02 PM, <ebiederm@xmission.com> wrote:
> Jordan Glover Golden_Miller83@protonmail.ch writes: > > > Hi, recently I hit system freeze after I was closing few containerized apps on my system. As for now it occurred only once on linux 5.14.3. I think it maybe be related to "Count rlimits in each user namespace" patchset merged during 5.14 window > > > > https://lore.kernel.org/all/257aa5fb1a7d81cf0f4c34f39ada2320c4284771.1619094428.git.legion@kernel.org/T/#u > > So that warning comes from: > > void dec_ucount(struct ucounts *ucounts, enum ucount_type type) > > { > > struct ucounts *iter; > > for (iter = ucounts; iter; iter = iter->ns->ucounts) { > > long dec = atomic_long_dec_if_positive(&iter->ucount[type]); > > WARN_ON_ONCE(dec < 0); > } > put_ucounts(ucounts); > > > } > > Which certainly looks like a reference count bug. It could also be a > > memory stomp somewhere close. > > Do you have any idea what else was going on? This location is the > > symptom but not the actual cause. > > Eric
I had about 2 containerized (flatpak/bubblewrap) apps (browser + music player) running . I quickly closed them with intent to shutdown the system but instead get the freeze and had to use magic sysrq to reboot. System logs end with what I posted and before there is nothing suspicious.
Maybe it's some random fluke. I'll reply if I hit it again.
Jordan
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