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[2620:137:e000::1:20]) by mx.google.com with ESMTP id i7-20020a1709064fc700b007ae61d89b3esi9710190ejw.356.2022.11.14.02.51.06; Mon, 14 Nov 2022 02:51:29 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=huawei.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236251AbiKNKqS (ORCPT + 99 others); Mon, 14 Nov 2022 05:46:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43380 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235997AbiKNKqP (ORCPT ); Mon, 14 Nov 2022 05:46:15 -0500 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BA162C2C; Mon, 14 Nov 2022 02:46:13 -0800 (PST) Received: from dggpeml500021.china.huawei.com (unknown [172.30.72.55]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4N9mDw3s1Wz15Mf2; Mon, 14 Nov 2022 18:45:52 +0800 (CST) Received: from dggpeml100012.china.huawei.com (7.185.36.121) by dggpeml500021.china.huawei.com (7.185.36.21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 14 Nov 2022 18:46:11 +0800 Received: from localhost.localdomain (10.67.175.61) by dggpeml100012.china.huawei.com (7.185.36.121) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 14 Nov 2022 18:46:11 +0800 From: Zheng Yejian To: , CC: , , Subject: [PATCH] tracing: Fix potential null-pointer-access of entry in list 'tr->err_log' Date: Mon, 14 Nov 2022 18:46:32 +0800 Message-ID: <20221114104632.3547266-1-zhengyejian1@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Originating-IP: [10.67.175.61] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpeml100012.china.huawei.com (7.185.36.121) X-CFilter-Loop: Reflected X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1749468409898724623?= X-GMAIL-MSGID: =?utf-8?q?1749468409898724623?= Entries in list 'tr->err_log' will be reused after entry number exceed TRACING_LOG_ERRS_MAX. The cmd string of the to be reused entry will be freed first then allocated a new one. If the allocation failed, then the entry will still be in list 'tr->err_log' but its 'cmd' field is set to be NULL, later access of 'cmd' is risky. Currently above problem can cause the loss of 'cmd' information of first entry in 'tr->err_log'. When execute `cat /sys/kernel/tracing/error_log`, reproduce logs like: [ 37.495100] trace_kprobe: error: Maxactive is not for kprobe(null) ^ [ 38.412517] trace_kprobe: error: Maxactive is not for kprobe Command: p4:myprobe2 do_sys_openat2 ^ Fixes: 1581a884b7ca ("tracing: Remove size restriction on tracing_log_err cmd strings") Signed-off-by: Zheng Yejian Acked-by: Masami Hiramatsu (Google) --- kernel/trace/trace.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 47a44b055a1d..5ae776598106 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -7802,6 +7802,7 @@ static struct tracing_log_err *get_tracing_log_err(struct trace_array *tr, int len) { struct tracing_log_err *err; + char *cmd; if (tr->n_err_log_entries < TRACING_LOG_ERRS_MAX) { err = alloc_tracing_log_err(len); @@ -7810,12 +7811,12 @@ static struct tracing_log_err *get_tracing_log_err(struct trace_array *tr, return err; } - + cmd = kzalloc(len, GFP_KERNEL); + if (!cmd) + return ERR_PTR(-ENOMEM); err = list_first_entry(&tr->err_log, struct tracing_log_err, list); kfree(err->cmd); - err->cmd = kzalloc(len, GFP_KERNEL); - if (!err->cmd) - return ERR_PTR(-ENOMEM); + err->cmd = cmd; list_del(&err->list); return err;