linux-kernel - [PATCH v3 1/2] tracing: Fix memory leak in test_gen_synth_cmd() and test_empty_synth

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Message-ID: <20221117012346.22647-2-shangxiaojing@huawei.com>
Date:   Thu, 17 Nov 2022 09:23:45 +0800
From:   Shang XiaoJing <shangxiaojing@...wei.com>
To:     <rostedt@...dmis.org>, <mhiramat@...nel.org>, <zanussi@...nel.org>,
        <fengguang.wu@...el.com>, <linux-kernel@...r.kernel.org>
CC:     <shangxiaojing@...wei.com>
Subject: [PATCH v3 1/2] tracing: Fix memory leak in test_gen_synth_cmd() and test_empty_synth_event()

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 <shangxiaojing@...wei.com>
---
changes in v2:
- adjust code for clean.
---
 kernel/trace/synth_event_gen_test.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/kernel/trace/synth_event_gen_test.c b/kernel/trace/synth_event_gen_test.c
index 0b15e975d2c2..8d77526892f4 100644
--- a/kernel/trace/synth_event_gen_test.c
+++ b/kernel/trace/synth_event_gen_test.c
@@ -120,15 +120,13 @@ 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));
- out:
+ free:
+	kfree(buf);
 	return ret;
  delete:
 	/* We got an error after creating the event, delete it */
 	synth_event_delete("gen_synth_test");
- free:
-	kfree(buf);
-
-	goto out;
+	goto free;
 }
 
 /*
@@ -227,15 +225,13 @@ 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));
- out:
+ free:
+	kfree(buf);
 	return ret;
  delete:
 	/* We got an error after creating the event, delete it */
 	synth_event_delete("empty_synth_test");
- free:
-	kfree(buf);
-
-	goto out;
+	goto free;
 }
 
 static struct synth_field_desc create_synth_test_fields[] = {
-- 
2.17.1