[1/2] tracing: Fix memory leak in test_gen_synth_cmd() and test_empty_synth_event()
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From: Shang XiaoJing <shangxiaojing@huawei.com>
To: <rostedt@goodmis.org>, <mhiramat@kernel.org>, <zanussi@kernel.org>,
<fengguang.wu@intel.com>, <linux-kernel@vger.kernel.org>
CC: <shangxiaojing@huawei.com>
Subject: [PATCH 1/2] tracing: Fix memory leak in test_gen_synth_cmd() and
test_empty_synth_event()
Date: Tue, 8 Nov 2022 16:31:22 +0800
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| Series |
tracing: Fix some bug about synth
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Commit Message
Shang XiaoJing
Nov. 8, 2022, 8:31 a.m. UTC
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@huawei.com>
---
kernel/trace/synth_event_gen_test.c | 2 ++
1 file changed, 2 insertions(+)
Comments
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 <shangxiaojing@huawei.com> > --- > 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? Tom
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 <shangxiaojing@huawei.com> >> --- >> 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,
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: