Re: [PATCH] trace: Avoid memory leak in predicate_parse()

[Tomas Bortoli <tomasbortoli@gmail.com>]

On 5/28/19 5:48 PM, Steven Rostedt wrote:
> On Tue, 28 May 2019 17:43:38 +0200
> Tomas Bortoli <tomasbortoli@gmail.com> wrote:
> 
>> In case of errors, predicate_parse() goes to the out_free label
>> to free memory and to return an error code.
>>
>> However, predicate_parse() does not free the predicates of the
>> temporary prog_stack array, thence leaking them.
> 
> Thanks, I applied this and I'm running it through my tests. But just an
> FYI, when sending updated patches please add a "v2" to the subject:
> 
>  [PATCH v2] tracing: Avoid memory leak in predicate_parse()
> 
> That way struggling maintainers like myself don't get confused about
> which patch to apply ;-)
> 
> Thanks!
> 

Yeah, sorry about that, will make sure it doesn't happen again!

Thank you,
Tomas


> 
>>
>> Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
>> Reported-by: syzbot+6b8e0fb820e570c59e19@syzkaller.appspotmail.com
>> ---
>>  kernel/trace/trace_events_filter.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
>> index 05a66493a164..ecfa6f0f1c7e 100644
>> --- a/kernel/trace/trace_events_filter.c
>> +++ b/kernel/trace/trace_events_filter.c
>> @@ -427,7 +427,7 @@ predicate_parse(const char *str, int nr_parens, int nr_preds,
>>  	op_stack = kmalloc_array(nr_parens, sizeof(*op_stack), GFP_KERNEL);
>>  	if (!op_stack)
>>  		return ERR_PTR(-ENOMEM);
>> -	prog_stack = kmalloc_array(nr_preds, sizeof(*prog_stack), GFP_KERNEL);
>> +	prog_stack = kcalloc(nr_preds, sizeof(*prog_stack), GFP_KERNEL);
>>  	if (!prog_stack) {
>>  		parse_error(pe, -ENOMEM, 0);
>>  		goto out_free;
>> @@ -578,6 +578,8 @@ predicate_parse(const char *str, int nr_parens, int nr_preds,
>>  out_free:
>>  	kfree(op_stack);
>>  	kfree(inverts);
>> +	for (i = 0; prog_stack[i].pred; i++)
>> +		kfree(prog_stack[i].pred);
>>  	kfree(prog_stack);
>>  	return ERR_PTR(ret);
>>  }
>