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[2620:137:e000::1:20]) by mx.google.com with ESMTP id i62-20020a626d41000000b0056e770672c1si13941434pfc.305.2022.11.29.03.41.50; Tue, 29 Nov 2022 03:42:03 -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 S229973AbiK2Ldm (ORCPT + 99 others); Tue, 29 Nov 2022 06:33:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39604 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233140AbiK2LdV (ORCPT ); Tue, 29 Nov 2022 06:33:21 -0500 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EEB17D95 for ; Tue, 29 Nov 2022 03:33:09 -0800 (PST) Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.57]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4NM0Vd6S4GzJnyB; Tue, 29 Nov 2022 19:29:45 +0800 (CST) Received: from kwepemm600003.china.huawei.com (7.193.23.202) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Tue, 29 Nov 2022 19:33:08 +0800 Received: from ubuntu1804.huawei.com (10.67.174.61) by kwepemm600003.china.huawei.com (7.193.23.202) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Tue, 29 Nov 2022 19:33:07 +0800 From: Yang Jihong To: , , CC: Subject: [PATCH v4] tracing: Fix infinite loop in tracing_read_pipe on overflowed print_trace_line Date: Tue, 29 Nov 2022 19:30:09 +0800 Message-ID: <20221129113009.182425-1-yangjihong1@huawei.com> X-Mailer: git-send-email 2.30.GIT MIME-Version: 1.0 X-Originating-IP: [10.67.174.61] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemm600003.china.huawei.com (7.193.23.202) 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?1750382758611688340?= X-GMAIL-MSGID: =?utf-8?q?1750830545399151426?= print_trace_line may overflow seq_file buffer. If the event is not consumed, the while loop keeps peeking this event, causing a infinite loop. Signed-off-by: Yang Jihong --- kernel/trace/trace.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index a7fe0e115272..de7c99f4b539 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6787,7 +6787,20 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, ret = print_trace_line(iter); if (ret == TRACE_TYPE_PARTIAL_LINE) { - /* don't print partial lines */ + /* + * If one print_trace_line() fills entire trace_seq in one shot, + * trace_seq_to_user() will returns -EBUSY because save_len == 0, + * In this case, we need to consume it, otherwise, loop will peek + * this event next time, resulting in an infinite loop. + */ + if (save_len == 0) { + iter->seq.full = 0; + trace_seq_puts(&iter->seq, "[LINE TOO BIG]\n"); + trace_consume(iter); + break; + } + + /* In other cases, don't print partial lines */ iter->seq.seq.len = save_len; break; }