From mboxrd@z Thu Jan 1 00:00:00 1970 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 F2144C83F1C for ; Mon, 28 Aug 2023 10:28:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231345AbjH1K2P (ORCPT ); Mon, 28 Aug 2023 06:28:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48194 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231411AbjH1K16 (ORCPT ); Mon, 28 Aug 2023 06:27:58 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 714AAB9 for ; Mon, 28 Aug 2023 03:27:55 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 07DE863B8F for ; Mon, 28 Aug 2023 10:27:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1E00FC433C7; Mon, 28 Aug 2023 10:27:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1693218474; bh=zEHA5PkNWABtaxztyVT2ydQM0EBHKJI1m7YLPPv/aIU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iYBIlAGriV8Dysm0qys7u9db/6nO3N2T5kr7EssjbrQTrjCAe0sfk806s4mxkli2K c+84n04Imqvm632VQk6glPCQsDUT73I9JYKY7TKilqApR3gkhDaEIwqdHkI4LWJeSP yCleKPqZpY95YV7dbvOwu2d4bVG5IwRwkz98XNks= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Zheng Yejian , "Steven Rostedt (Google)" , Sasha Levin Subject: [PATCH 4.19 101/129] tracing: Fix memleak due to race between current_tracer and trace Date: Mon, 28 Aug 2023 12:13:15 +0200 Message-ID: <20230828101156.993810953@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230828101153.030066927@linuxfoundation.org> References: <20230828101153.030066927@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zheng Yejian [ Upstream commit eecb91b9f98d6427d4af5fdb8f108f52572a39e7 ] Kmemleak report a leak in graph_trace_open(): unreferenced object 0xffff0040b95f4a00 (size 128): comm "cat", pid 204981, jiffies 4301155872 (age 99771.964s) hex dump (first 32 bytes): e0 05 e7 b4 ab 7d 00 00 0b 00 01 00 00 00 00 00 .....}.......... f4 00 01 10 00 a0 ff ff 00 00 00 00 65 00 10 00 ............e... backtrace: [<000000005db27c8b>] kmem_cache_alloc_trace+0x348/0x5f0 [<000000007df90faa>] graph_trace_open+0xb0/0x344 [<00000000737524cd>] __tracing_open+0x450/0xb10 [<0000000098043327>] tracing_open+0x1a0/0x2a0 [<00000000291c3876>] do_dentry_open+0x3c0/0xdc0 [<000000004015bcd6>] vfs_open+0x98/0xd0 [<000000002b5f60c9>] do_open+0x520/0x8d0 [<00000000376c7820>] path_openat+0x1c0/0x3e0 [<00000000336a54b5>] do_filp_open+0x14c/0x324 [<000000002802df13>] do_sys_openat2+0x2c4/0x530 [<0000000094eea458>] __arm64_sys_openat+0x130/0x1c4 [<00000000a71d7881>] el0_svc_common.constprop.0+0xfc/0x394 [<00000000313647bf>] do_el0_svc+0xac/0xec [<000000002ef1c651>] el0_svc+0x20/0x30 [<000000002fd4692a>] el0_sync_handler+0xb0/0xb4 [<000000000c309c35>] el0_sync+0x160/0x180 The root cause is descripted as follows: __tracing_open() { // 1. File 'trace' is being opened; ... *iter->trace = *tr->current_trace; // 2. Tracer 'function_graph' is // currently set; ... iter->trace->open(iter); // 3. Call graph_trace_open() here, // and memory are allocated in it; ... } s_start() { // 4. The opened file is being read; ... *iter->trace = *tr->current_trace; // 5. If tracer is switched to // 'nop' or others, then memory // in step 3 are leaked!!! ... } To fix it, in s_start(), close tracer before switching then reopen the new tracer after switching. And some tracers like 'wakeup' may not update 'iter->private' in some cases when reopen, then it should be cleared to avoid being mistakenly closed again. Link: https://lore.kernel.org/linux-trace-kernel/20230817125539.1646321-1-zhengyejian1@huawei.com Fixes: d7350c3f4569 ("tracing/core: make the read callbacks reentrants") Signed-off-by: Zheng Yejian Signed-off-by: Steven Rostedt (Google) Signed-off-by: Sasha Levin --- kernel/trace/trace.c | 9 ++++++++- kernel/trace/trace_irqsoff.c | 3 ++- kernel/trace/trace_sched_wakeup.c | 2 ++ 3 files changed, 12 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 9da7b10e56d23..f44c8f1fd3ec5 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3277,8 +3277,15 @@ static void *s_start(struct seq_file *m, loff_t *pos) * will point to the same string as current_trace->name. */ mutex_lock(&trace_types_lock); - if (unlikely(tr->current_trace && iter->trace->name != tr->current_trace->name)) + if (unlikely(tr->current_trace && iter->trace->name != tr->current_trace->name)) { + /* Close iter->trace before switching to the new current tracer */ + if (iter->trace->close) + iter->trace->close(iter); *iter->trace = *tr->current_trace; + /* Reopen the new current tracer */ + if (iter->trace->open) + iter->trace->open(iter); + } mutex_unlock(&trace_types_lock); #ifdef CONFIG_TRACER_MAX_TRACE diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c index 98ea6d28df15d..0f36bb59970df 100644 --- a/kernel/trace/trace_irqsoff.c +++ b/kernel/trace/trace_irqsoff.c @@ -222,7 +222,8 @@ static void irqsoff_trace_open(struct trace_iterator *iter) { if (is_graph(iter->tr)) graph_trace_open(iter); - + else + iter->private = NULL; } static void irqsoff_trace_close(struct trace_iterator *iter) diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c index 11f4dbd9526b6..8041bd5e42624 100644 --- a/kernel/trace/trace_sched_wakeup.c +++ b/kernel/trace/trace_sched_wakeup.c @@ -287,6 +287,8 @@ static void wakeup_trace_open(struct trace_iterator *iter) { if (is_graph(iter->tr)) graph_trace_open(iter); + else + iter->private = NULL; } static void wakeup_trace_close(struct trace_iterator *iter) -- 2.40.1