From: ebiederm@xmission.com (Eric W. Biederman)
To: Rune Kleveland <rune.kleveland@infomedia.dk>
Cc: Yu Zhao <yuzhao@google.com>, Alexey Gladkov <legion@kernel.org>,
Jordan Glover <Golden_Miller83@protonmail.ch>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, containers@lists.linux-foundation.org
Subject: Re: linux 5.14.3: free_user_ns causes NULL pointer dereference
Date: Tue, 12 Oct 2021 12:31:00 -0500 [thread overview]
Message-ID: <87o87u2lrf.fsf@disp2133> (raw)
In-Reply-To: <ccbccf82-dc50-00b2-1cfd-3da5e2c81dbf@infomedia.dk> (Rune Kleveland's message of "Sun, 10 Oct 2021 10:59:10 +0200")
Rune Kleveland <rune.kleveland@infomedia.dk> writes:
> Hi!
>
> Just wanted to let you know that I still get these on stock Fedora kernel
> 5.14.10 on the IBM blades. But it took 10 hours before the first server
> crashed. The other 4 still runs fine since 15 hours ago. So for me it seems more
> stable now, but that could just be a coincidence.
Alex and I have been working on this and we are still tracking down
whatever is going on.
While we haven't found the issue yet we have found a trivially correct
change that allows us to reproduce the issue faster.
Hopefully this will allow us to narrow down on whatever it is soon.
diff --git a/kernel/ucount.c b/kernel/ucount.c
index bb51849e6375..3b7e176cf7a2 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -203,6 +203,7 @@ void put_ucounts(struct ucounts *ucounts)
if (atomic_dec_and_lock_irqsave(&ucounts->count, &ucounts_lock, flags)) {
hlist_del_init(&ucounts->node);
+ ucounts->ns = NULL;
spin_unlock_irqrestore(&ucounts_lock, flags);
kfree(ucounts);
}
Eric
next prev parent reply other threads:[~2021-10-12 17:31 UTC|newest]
Thread overview: 58+ 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 21:02 ` Eric W. Biederman
2021-09-15 22:42 ` Jordan Glover
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
2021-10-06 7:57 ` Rune Kleveland
2021-10-10 8:59 ` Rune Kleveland
2021-10-11 13:09 ` Hillf Danton
2021-10-12 17:31 ` Eric W. Biederman [this message]
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
2021-10-16 2:08 ` Hillf Danton
2021-10-16 18:00 ` 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
2021-10-24 17:36 ` kernel test robot
2021-10-25 14:13 ` Eric W. Biederman
2021-11-06 5:05 ` kernel test robot
2021-11-06 5:05 ` kernel test robot
2021-11-06 20:22 ` kernel test robot
2021-11-06 20:22 ` kernel test robot
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
2021-10-11 13:39 ` linux 5.14.3: free_user_ns causes NULL pointer dereference Alexey Gladkov
2021-10-06 2:12 ` Hillf Danton
2021-10-06 6:22 ` Yu Zhao
2021-10-07 13:28 ` Jordan Glover
2021-10-10 11:26 ` Hillf Danton
2021-10-03 19:37 ` Jordan Glover
-- strict thread matches above, loose matches on Subject: below --
2021-10-20 7:39 Antoine Martin
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