From: Jordan Glover <Golden_Miller83@protonmail.ch>
To: ebiederm@xmission.com
Cc: LKML <linux-kernel@vger.kernel.org>,
"linux-mm\\@kvack.org" <linux-mm@kvack.org>,
"legion\\@kernel.org" <legion@kernel.org>,
"containers\\@lists.linux-foundation.org"
<containers@lists.linux-foundation.org>
Subject: Re: linux 5.14.3: free_user_ns causes NULL pointer dereference
Date: Wed, 15 Sep 2021 22:42:21 +0000 [thread overview]
Message-ID: <OJK-F2NSBlem52GqvCQYzaVxs2x9Csq3qO4QbTG4A4UUNaQpebpAQmyyKzUd70CIo27C4K7CL3bhIzcxulIzYMu067QOMXCFz8ejh3ZtFhE=@protonmail.ch> (raw)
In-Reply-To: <87ee9pa6xw.fsf@disp2133>
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
next prev parent reply other threads:[~2021-09-15 22:44 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-15 19:49 linux 5.14.3: free_user_ns causes NULL pointer dereference Jordan Glover
2021-09-15 21:02 ` Eric W. Biederman
2021-09-15 22:42 ` Jordan Glover [this message]
2021-09-15 23:44 ` Yu Zhao
2021-09-17 16:15 ` Eric W. Biederman
2021-09-17 18:45 ` Yu Zhao
2021-09-15 23:47 ` Jordan Glover
2021-09-16 17:30 ` Eric W. Biederman
2021-09-16 19:14 ` Alexey Gladkov
2021-09-28 13:40 ` Jordan Glover
2021-09-29 17:36 ` Alexey Gladkov
2021-09-29 21:39 ` Jordan Glover
2021-09-30 13:06 ` Alexey Gladkov
2021-09-30 22:27 ` Yu Zhao
2021-10-04 17:10 ` Eric W. Biederman
2021-10-04 17:19 ` Eric W. Biederman
2021-10-04 21:34 ` Yu Zhao
2021-10-11 13:39 ` Alexey Gladkov
[not found] ` <ccbccf82-dc50-00b2-1cfd-3da5e2c81dbf@infomedia.dk>
2021-10-12 17:31 ` Eric W. Biederman
2021-10-15 22:10 ` [CFT][PATCH] ucounts: Fix signal ucount refcounting Eric W. Biederman
2021-10-15 23:09 ` Alexey Gladkov
2021-10-16 17:34 ` Eric W. Biederman
2021-10-17 19:35 ` Yu Zhao
2021-10-18 15:35 ` Eric W. Biederman
2021-10-17 16:47 ` Rune Kleveland
2021-10-18 6:25 ` Yu Zhao
2021-10-18 10:31 ` Jordan Glover
2021-10-18 16:06 ` [PATCH v2] " Eric W. Biederman
2021-10-18 17:21 ` [PATCH 0/3] ucounts: misc fixes Eric W. Biederman
2021-10-18 17:23 ` [PATCH 1/3] ucounts: Pair inc_rlimit_ucounts with dec_rlimit_ucoutns in commit_creds Eric W. Biederman
2021-10-18 17:23 ` [PATCH 2/3] ucounts: Proper error handling in set_cred_ucounts Eric W. Biederman
2021-10-18 17:24 ` [PATCH 3/3] ucounts: Move get_ucounts from cred_alloc_blank to key_change_session_keyring Eric W. Biederman
2021-10-18 17:54 ` [PATCH 0/4] ucounts: misc cleanups Eric W. Biederman
2021-10-18 17:55 ` [PATCH 1/4] ucounts: In set_cred_ucounts assume new->ucounts is non-NULL Eric W. Biederman
2021-10-18 17:56 ` [PATCH 2/4] ucounts: Remove unnecessary test for NULL ucount in get_ucounts Eric W. Biederman
2021-10-18 17:56 ` [PATCH 3/4] ucounts: Add get_ucounts_or_wrap for clarity Eric W. Biederman
2021-10-18 17:57 ` [PATCH 4/4] ucounts: Use atomic_long_sub_return " Eric W. Biederman
2021-10-18 22:29 ` [PATCH 0/4] ucounts: misc cleanups Yu Zhao
2021-10-18 22:28 ` [PATCH 0/3] ucounts: misc fixes Yu Zhao
2021-10-18 22:26 ` [PATCH v2] ucounts: Fix signal ucount refcounting Yu Zhao
[not found] ` <20211016020833.1538-1-hdanton@sina.com>
2021-10-16 18:00 ` [CFT][PATCH] " Eric W. Biederman
[not found] ` <20211006021219.2010-1-hdanton@sina.com>
2021-10-06 6:22 ` linux 5.14.3: free_user_ns causes NULL pointer dereference Yu Zhao
2021-10-07 13:28 ` Jordan Glover
2021-10-03 19:37 ` Jordan Glover
2021-10-20 7:39 Antoine Martin
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