Some bugs are found when insert synth_event_gen_test, and fixed by this
patch set.
Shang XiaoJing (2):
tracing: Fix memory leak in test_gen_synth_cmd() and
test_empty_synth_event()
tracing: Fix wild-memory-access in register_synth_event()
kernel/trace/synth_event_gen_test.c | 2 ++
kernel/trace/trace_events_synth.c | 2 ++
2 files changed, 4 insertions(+)
--
2.17.1
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 <[email protected]>
---
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:
--
2.17.1
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 <[email protected]>
> ---
> 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 <[email protected]>
>> ---
>> 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