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 B3D70C4332F for ; Sun, 13 Nov 2022 06:48:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235067AbiKMGsl (ORCPT ); Sun, 13 Nov 2022 01:48:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54504 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231694AbiKMGsh (ORCPT ); Sun, 13 Nov 2022 01:48:37 -0500 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 40A24AE79 for ; Sat, 12 Nov 2022 22:48:34 -0800 (PST) Received: from kwepemi500016.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4N930v43cRzHvkd; Sun, 13 Nov 2022 14:47:59 +0800 (CST) Received: from [10.174.176.230] (10.174.176.230) by kwepemi500016.china.huawei.com (7.221.188.220) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Sun, 13 Nov 2022 14:48:27 +0800 Message-ID: <48ff4656-dd3e-b70e-0733-66ac37249bf5@huawei.com> Date: Sun, 13 Nov 2022 14:48:25 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.1.0 Subject: Re: [PATCH 1/2] tracing: Fix memory leak in test_gen_synth_cmd() and test_empty_synth_event() To: Tom Zanussi , , , , References: <20221108083124.27218-1-shangxiaojing@huawei.com> <20221108083124.27218-2-shangxiaojing@huawei.com> <1b1d42582c2c9957dc47cd25b50f566b305fb14b.camel@kernel.org> From: shangxiaojing In-Reply-To: <1b1d42582c2c9957dc47cd25b50f566b305fb14b.camel@kernel.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.176.230] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemi500016.china.huawei.com (7.221.188.220) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/11/13 5:12, Tom Zanussi wrote: > Hi Shang, > > Thanks for finding this bug, comment below... > > On Tue, 2022-11-08 at 16:31 +0800, Shang XiaoJing wrote: >> test_gen_synth_cmd() only free buf in fail path, hence buf will leak >> when there is no failure. Add kfree(buf) to prevent the memleak. The >> same reason and solution in test_empty_synth_event(). >> >> unreferenced object 0xffff8881127de000 (size 2048): >>   comm "modprobe", pid 247, jiffies 4294972316 (age 78.756s) >>   hex dump (first 32 bytes): >>     20 67 65 6e 5f 73 79 6e 74 68 5f 74 65 73 74 20   gen_synth_test >>     20 70 69 64 5f 74 20 6e 65 78 74 5f 70 69 64 5f   pid_t next_pid_ >>   backtrace: >>     [<000000004254801a>] kmalloc_trace+0x26/0x100 >>     [<0000000039eb1cf5>] 0xffffffffa00083cd >>     [<000000000e8c3bc8>] 0xffffffffa00086ba >>     [<00000000c293d1ea>] do_one_initcall+0xdb/0x480 >>     [<00000000aa189e6d>] do_init_module+0x1cf/0x680 >>     [<00000000d513222b>] load_module+0x6a50/0x70a0 >>     [<000000001fd4d529>] __do_sys_finit_module+0x12f/0x1c0 >>     [<00000000b36c4c0f>] do_syscall_64+0x3f/0x90 >>     [<00000000bbf20cf3>] entry_SYSCALL_64_after_hwframe+0x63/0xcd >> unreferenced object 0xffff8881127df000 (size 2048): >>   comm "modprobe", pid 247, jiffies 4294972324 (age 78.728s) >>   hex dump (first 32 bytes): >>     20 65 6d 70 74 79 5f 73 79 6e 74 68 5f 74 65 73   empty_synth_tes >>     74 20 20 70 69 64 5f 74 20 6e 65 78 74 5f 70 69  t  pid_t next_pi >>   backtrace: >>     [<000000004254801a>] kmalloc_trace+0x26/0x100 >>     [<00000000d4db9a3d>] 0xffffffffa0008071 >>     [<00000000c31354a5>] 0xffffffffa00086ce >>     [<00000000c293d1ea>] do_one_initcall+0xdb/0x480 >>     [<00000000aa189e6d>] do_init_module+0x1cf/0x680 >>     [<00000000d513222b>] load_module+0x6a50/0x70a0 >>     [<000000001fd4d529>] __do_sys_finit_module+0x12f/0x1c0 >>     [<00000000b36c4c0f>] do_syscall_64+0x3f/0x90 >>     [<00000000bbf20cf3>] entry_SYSCALL_64_after_hwframe+0x63/0xcd >> >> Fixes: 9fe41efaca08 ("tracing: Add synth event generation test >> module") >> Signed-off-by: Shang XiaoJing >> --- >>  kernel/trace/synth_event_gen_test.c | 2 ++ >>  1 file changed, 2 insertions(+) >> >> diff --git a/kernel/trace/synth_event_gen_test.c >> b/kernel/trace/synth_event_gen_test.c >> index 0b15e975d2c2..db1ec4809ad1 100644 >> --- a/kernel/trace/synth_event_gen_test.c >> +++ b/kernel/trace/synth_event_gen_test.c >> @@ -120,6 +120,7 @@ static int __init test_gen_synth_cmd(void) >> >>         /* Now generate a gen_synth_test event */ >>         ret = synth_event_trace_array(gen_synth_test, vals, >> ARRAY_SIZE(vals)); >> +       kfree(buf); >>   out: >>         return ret; >>   delete: >> @@ -227,6 +228,7 @@ static int __init test_empty_synth_event(void) >> >>         /* Now trace an empty_synth_test event */ >>         ret = synth_event_trace_array(empty_synth_test, vals, >> ARRAY_SIZE(vals)); >> +       kfree(buf); >>   out: >>         return ret; >>   delete: > > Makes sense, and if you do this then you could probably remove the > other kfree() at the bottom and clean the code up a bit, like change > this: > > /* Now generate a gen_synth_test event */ > ret = synth_event_trace_array(gen_synth_test, vals, ARRAY_SIZE(vals)); > kfree(buf); > out: > return ret; > delete: > /* We got an error after creating the event, delete it */ > synth_event_delete("gen_synth_test"); > free: > kfree(buf); > > goto out; > } > > to this: > > /* Now generate a gen_synth_test event */ > ret = synth_event_trace_array(gen_synth_test, vals, ARRAY_SIZE(vals)); > free: > kfree(buf); > return ret; > delete: > /* We got an error after creating the event, delete it */ > synth_event_delete("gen_synth_test"); > goto free; > } > > What do you think? > Right, I thought maybe less change is better for the bugfix. It looks better to carry some clean up, thanks for the review, will fix in v2. Thanks, -- Shang XiaoJing