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 4B244C7EE2D for ; Sat, 25 Feb 2023 10:13:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229577AbjBYKNk (ORCPT ); Sat, 25 Feb 2023 05:13:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37700 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229496AbjBYKNi (ORCPT ); Sat, 25 Feb 2023 05:13:38 -0500 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 69DAB12BD0 for ; Sat, 25 Feb 2023 02:13:37 -0800 (PST) Received: from dggpemm500013.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4PP2Zv0wDDzRsJd; Sat, 25 Feb 2023 18:10:47 +0800 (CST) Received: from ubuntu1804.huawei.com (10.67.175.36) by dggpemm500013.china.huawei.com (7.185.36.172) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.17; Sat, 25 Feb 2023 18:13:35 +0800 From: Chen Zhongjin To: CC: , , , , Subject: [PATCH v2] x86: profiling: Check prof_buffer in profile_tick() Date: Sat, 25 Feb 2023 18:11:29 +0800 Message-ID: <20230225101129.66648-1-chenzhongjin@huawei.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.67.175.36] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemm500013.china.huawei.com (7.185.36.172) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org KASAN reported a UAF problem in profile_tick(): BUG: KASAN: use-after-free in profile_tick+0x5c/0x80 Read of size 8 at addr ffff888100928aa0 by task bash/1108 CPU: 2 PID: 1108 Comm: bash Not tainted 5.10.0+ #72 Call Trace: dump_stack+0x93/0xc5 print_address_description.constprop.0+0x1c/0x3c0 kasan_report.cold+0x37/0x74 check_memory_region+0x161/0x1c0 profile_tick+0x5c/0x80 tick_sched_timer+0xcd/0x100 __hrtimer_run_queues+0x23e/0x480 hrtimer_interrupt+0x1c2/0x440 asm_call_irq_on_stack+0xf/0x20 ... It is beacause in profiling_store(), profile_init() is possible to fail and free prof_cpu_mask. However prof_cpu_mask is not set to NULL and cpumask_available(prof_cpu_mask) will return true in profile_tick(). Then cpumask_test_cpu() will dereference prof_cpu_mask and trigger the KASAN warning. There is no interface to disable profile_tick() even though profile_init has been already failed. And when CONFIG_CPUMASK_OFFSTACK=n, cpumask_var_t is an array pointer which can not be set to NULL. So prof_cpu_mask can be a freed pointner or uncleaned array here, and cpumask_available() can't promise it is safe to use it. To fix this, add check for prof_buffer in profile_tick() before check cpumask_available(prof_cpu_mask). Because prof_cpu_mask is available only after prof_buffer is allocated successfully. Fixes: c309b917cab5 ("cpumask: convert kernel/profile.c") Signed-off-by: Chen Zhongjin --- v1 [https://lore.kernel.org/lkml/202302250609.vmze90DB-lkp@intel.com/T/] -> v2: Only check prof_buffer in profile_tick() but not set prof_cpu_mask to NULL after free_cpumask_var() --- kernel/profile.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/profile.c b/kernel/profile.c index 8a77769bc4b4..cca47dc2b1db 100644 --- a/kernel/profile.c +++ b/kernel/profile.c @@ -334,7 +334,7 @@ void profile_tick(int type) { struct pt_regs *regs = get_irq_regs(); - if (!user_mode(regs) && cpumask_available(prof_cpu_mask) && + if (!user_mode(regs) && prof_buffer && cpumask_available(prof_cpu_mask) && cpumask_test_cpu(smp_processor_id(), prof_cpu_mask)) profile_hit(type, (void *)profile_pc(regs)); } -- 2.17.1