[PATCH v3 1/2] tracing: Fix memory leak in test_gen_synth_cmd() and test_empty_synth_event()

From: Shang XiaoJing
Date: Wed Nov 16 2022 - 20:25:28 EST


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@xxxxxxxxxx>
---
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