From patchwork Tue Aug 8 12:14:35 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: cuigaosheng X-Patchwork-Id: 13346363 X-Patchwork-Delegate: paul@paul-moore.com Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E8B08C05052 for ; Tue, 8 Aug 2023 16:33:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232790AbjHHQdW (ORCPT ); Tue, 8 Aug 2023 12:33:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58110 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233067AbjHHQcJ (ORCPT ); Tue, 8 Aug 2023 12:32:09 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 047173100E for ; Tue, 8 Aug 2023 08:51:56 -0700 (PDT) Received: from kwepemd500002.china.huawei.com (unknown [172.30.72.56]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4RKsXk2M5Vz1L8xj; Tue, 8 Aug 2023 20:13:26 +0800 (CST) Received: from cgs.huawei.com (10.244.148.83) by kwepemd500002.china.huawei.com (7.221.188.104) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.2.1258.16; Tue, 8 Aug 2023 20:14:35 +0800 From: Gaosheng Cui To: , , CC: Subject: [PATCH v2] audit: fix possible soft lockup in __audit_inode_child() Date: Tue, 8 Aug 2023 20:14:35 +0800 Message-ID: <20230808121435.1118761-1-cuigaosheng1@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Originating-IP: [10.244.148.83] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To kwepemd500002.china.huawei.com (7.221.188.104) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: audit@vger.kernel.org Tracefs or debugfs maybe cause hundreds to thousands of PATH records, too many PATH records maybe cause soft lockup. For example: 1. CONFIG_KASAN=y && CONFIG_PREEMPTION=n 2. auditctl -a exit,always -S open -k key 3. sysctl -w kernel.watchdog_thresh=5 4. mkdir /sys/kernel/debug/tracing/instances/test There may be a soft lockup as follows: watchdog: BUG: soft lockup - CPU#45 stuck for 7s! [mkdir:15498] Kernel panic - not syncing: softlockup: hung tasks Call trace: dump_backtrace+0x0/0x30c show_stack+0x20/0x30 dump_stack+0x11c/0x174 panic+0x27c/0x494 watchdog_timer_fn+0x2bc/0x390 __run_hrtimer+0x148/0x4fc __hrtimer_run_queues+0x154/0x210 hrtimer_interrupt+0x2c4/0x760 arch_timer_handler_phys+0x48/0x60 handle_percpu_devid_irq+0xe0/0x340 __handle_domain_irq+0xbc/0x130 gic_handle_irq+0x78/0x460 el1_irq+0xb8/0x140 __audit_inode_child+0x240/0x7bc tracefs_create_file+0x1b8/0x2a0 trace_create_file+0x18/0x50 event_create_dir+0x204/0x30c __trace_add_new_event+0xac/0x100 event_trace_add_tracer+0xa0/0x130 trace_array_create_dir+0x60/0x140 trace_array_create+0x1e0/0x370 instance_mkdir+0x90/0xd0 tracefs_syscall_mkdir+0x68/0xa0 vfs_mkdir+0x21c/0x34c do_mkdirat+0x1b4/0x1d4 __arm64_sys_mkdirat+0x4c/0x60 el0_svc_common.constprop.0+0xa8/0x240 do_el0_svc+0x8c/0xc0 el0_svc+0x20/0x30 el0_sync_handler+0xb0/0xb4 el0_sync+0x160/0x180 Therefore, we add cond_resched() to __audit_inode_child() to fix it. Fixes: 5195d8e217a7 ("audit: dynamically allocate audit_names when not enough space is in the names array") Signed-off-by: Gaosheng Cui --- v2: - Add cond_resched() between the two loops, thanks! kernel/auditsc.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/auditsc.c b/kernel/auditsc.c index addeed3df15d..8dfd581cd554 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -2456,6 +2456,8 @@ void __audit_inode_child(struct inode *parent, } } + cond_resched(); + /* is there a matching child entry? */ list_for_each_entry(n, &context->names_list, list) { /* can only match entries that have a name */