From patchwork Fri Jan 15 14:57:22 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexey Gladkov X-Patchwork-Id: 12023031 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.7 required=3.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA9A7C433E0 for ; Fri, 15 Jan 2021 14:59:45 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 3017023370 for ; Fri, 15 Jan 2021 14:59:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3017023370 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-20651-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 17426 invoked by uid 550); 15 Jan 2021 14:59:22 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 16349 invoked from network); 15 Jan 2021 14:59:22 -0000 From: Alexey Gladkov To: LKML , io-uring@vger.kernel.org, Kernel Hardening , Linux Containers , linux-mm@kvack.org Cc: Alexey Gladkov , Andrew Morton , Christian Brauner , "Eric W . Biederman" , Jann Horn , Jens Axboe , Kees Cook , Linus Torvalds , Oleg Nesterov Subject: [RFC PATCH v3 1/8] Use refcount_t for ucounts reference counting Date: Fri, 15 Jan 2021 15:57:22 +0100 Message-Id: <116c7669744404364651e3b380db2d82bb23f983.1610722473.git.gladkov.alexey@gmail.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: References: MIME-Version: 1.0 X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.6.1 (raptor.unsafe.ru [5.9.43.93]); Fri, 15 Jan 2021 14:59:10 +0000 (UTC) Signed-off-by: Alexey Gladkov Reported-by: kernel test robot --- include/linux/user_namespace.h | 2 +- kernel/ucount.c | 20 +++++++------------- 2 files changed, 8 insertions(+), 14 deletions(-) diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h index 64cf8ebdc4ec..f84fc2d9ce20 100644 --- a/include/linux/user_namespace.h +++ b/include/linux/user_namespace.h @@ -92,7 +92,7 @@ struct ucounts { struct hlist_node node; struct user_namespace *ns; kuid_t uid; - int count; + refcount_t count; atomic_t ucount[UCOUNT_COUNTS]; }; diff --git a/kernel/ucount.c b/kernel/ucount.c index 11b1596e2542..82acd2226460 100644 --- a/kernel/ucount.c +++ b/kernel/ucount.c @@ -141,7 +141,8 @@ static struct ucounts *get_ucounts(struct user_namespace *ns, kuid_t uid) new->ns = ns; new->uid = uid; - new->count = 0; + + refcount_set(&new->count, 0); spin_lock_irq(&ucounts_lock); ucounts = find_ucounts(ns, uid, hashent); @@ -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; } @@ -164,15 +162,11 @@ static void put_ucounts(struct ucounts *ucounts) { unsigned long flags; - spin_lock_irqsave(&ucounts_lock, flags); - ucounts->count -= 1; - if (!ucounts->count) + if (refcount_dec_and_lock_irqsave(&ucounts->count, &ucounts_lock, &flags)) { hlist_del_init(&ucounts->node); - else - ucounts = NULL; - spin_unlock_irqrestore(&ucounts_lock, flags); - - kfree(ucounts); + spin_unlock_irqrestore(&ucounts_lock, flags); + kfree(ucounts); + } } static inline bool atomic_inc_below(atomic_t *v, int u)