From: Linus Torvalds <torvalds@linux-foundation.org>
To: Alexey Gladkov <gladkov.alexey@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
io-uring <io-uring@vger.kernel.org>,
Kernel Hardening <kernel-hardening@lists.openwall.com>,
Linux Containers <containers@lists.linux-foundation.org>,
Linux-MM <linux-mm@kvack.org>,
Alexey Gladkov <legion@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Christian Brauner <christian.brauner@ubuntu.com>,
"Eric W . Biederman" <ebiederm@xmission.com>,
Jann Horn <jannh@google.com>, Jens Axboe <axboe@kernel.dk>,
Kees Cook <keescook@chromium.org>,
Oleg Nesterov <oleg@redhat.com>
Subject: Re: [RFC PATCH v3 1/8] Use refcount_t for ucounts reference counting
Date: Mon, 18 Jan 2021 11:14:48 -0800 [thread overview]
Message-ID: <CAHk-=wjsg0Lgf1Mh2UiJE4sqBDDo0VhFVBUbhed47ot2CQQwfQ@mail.gmail.com> (raw)
In-Reply-To: <116c7669744404364651e3b380db2d82bb23f983.1610722473.git.gladkov.alexey@gmail.com>
On Fri, Jan 15, 2021 at 6:59 AM Alexey Gladkov <gladkov.alexey@gmail.com> wrote:
>
> @@ -152,10 +153,7 @@ static struct ucounts *get_ucounts(struct user_namespace *ns, kuid_t uid)
> ucounts = new;
> }
> }
> - if (ucounts->count == INT_MAX)
> - ucounts = NULL;
> - else
> - ucounts->count += 1;
> + refcount_inc(&ucounts->count);
> spin_unlock_irq(&ucounts_lock);
> return ucounts;
> }
This is wrong.
It used to return NULL when the count saturated.
Now it just silently saturates.
I'm not sure how many people care, but that NULL return ends up being
returned quite widely (through "inc_uncount()" and friends).
The fact that this has no commit message at all to explain what it is
doing and why is also a grounds for just NAK.
Linus
next prev parent reply other threads:[~2021-01-18 19:15 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-15 14:57 [RFC PATCH v3 0/8] Count rlimits in each user namespace Alexey Gladkov
2021-01-15 14:57 ` [RFC PATCH v3 1/8] Use refcount_t for ucounts reference counting Alexey Gladkov
2021-01-18 6:06 ` c25050162e: WARNING:at_lib/refcount.c:#refcount_warn_saturate kernel test robot
2021-01-18 19:14 ` Linus Torvalds [this message]
2021-01-18 19:45 ` [RFC PATCH v3 1/8] Use refcount_t for ucounts reference counting Alexey Gladkov
2021-01-18 20:34 ` Linus Torvalds
2021-01-18 20:56 ` Alexey Gladkov
2021-01-19 4:35 ` Kaiwan N Billimoria
2021-01-20 1:57 ` Eric W. Biederman
2021-01-20 1:58 ` Eric W. Biederman
2021-01-21 12:04 ` Alexey Gladkov
2021-01-21 15:50 ` Eric W. Biederman
2021-01-21 16:07 ` Alexey Gladkov
2021-01-15 14:57 ` [RFC PATCH v3 2/8] Add a reference to ucounts for each cred Alexey Gladkov
2021-01-18 6:47 ` 14c3c8a27f: kernel_BUG_at_kernel/cred.c kernel test robot
2021-01-18 8:31 ` [PATCH v4 2/8] Add a reference to ucounts for each cred Alexey Gladkov
2021-01-15 14:57 ` [RFC PATCH v3 3/8] Move RLIMIT_NPROC counter to ucounts Alexey Gladkov
2021-01-15 14:57 ` [RFC PATCH v3 4/8] Move RLIMIT_MSGQUEUE " Alexey Gladkov
2021-01-15 14:57 ` [RFC PATCH v3 5/8] Move RLIMIT_SIGPENDING " Alexey Gladkov
2021-01-15 14:57 ` [RFC PATCH v3 6/8] Move RLIMIT_MEMLOCK " Alexey Gladkov
2021-01-15 14:57 ` [RFC PATCH v3 7/8] Move RLIMIT_NPROC check to the place where we increment the counter Alexey Gladkov
2021-01-15 14:57 ` [RFC PATCH v3 8/8] kselftests: Add test to check for rlimit changes in different user namespaces Alexey Gladkov
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