Re: [PATCH] samples/landlock: fix path_list memory leak

[Mickaël Salaün]

On 28/04/2021 17:36, Tom Rix wrote:
> 
> On 4/28/21 2:58 AM, Mickaël Salaün wrote:
>> On 27/04/2021 21:13, Nick Desaulniers wrote:
>>> On Tue, Apr 27, 2021 at 11:38 AM <trix@xxxxxxxxxx> wrote:
>>>> From: Tom Rix <trix@xxxxxxxxxx>
>>>>
>>>> Clang static analysis reports this error
>>>>
>>>> sandboxer.c:134:8: warning: Potential leak of memory
>>>>    pointed to by 'path_list'
>>>>          ret = 0;
>>>>                ^
>>>> path_list is allocated in parse_path() but never freed.
>>>>
>>>> Signed-off-by: Tom Rix <trix@xxxxxxxxxx>
>>>> ---
>>>>   samples/landlock/sandboxer.c | 2 ++
>>>>   1 file changed, 2 insertions(+)
>>>>
>>>> diff --git a/samples/landlock/sandboxer.c
>>>> b/samples/landlock/sandboxer.c
>>>> index 7a15910d2171..4629d011ed61 100644
>>>> --- a/samples/landlock/sandboxer.c
>>>> +++ b/samples/landlock/sandboxer.c
>>>> @@ -134,6 +134,8 @@ static int populate_ruleset(
>>>>          ret = 0;
>>>>
>>>>   out_free_name:
>>>> +       if (path_list)
>>>> +               free(path_list);
>>> I don't think the conditional is even necessary? By our first `goto
>>> out_free_name;`, `parse_path` has already been called/memory for
>>> `path_list` has already been allocated. `parse_path` doesn't check
>>> whether `malloc` has failed.
>> Indeed, no need for the path_list check. In practice, this memory leak
>> doesn't stay long because of the execve, but I missed this free anyway.
>> Thanks!
> 
> Ok, the general problem of not checking if malloc and friends succeeds
> is a different problem.
> 
> So remove the check and keep the free ?

Yes please.

> 
> Tom
> 
>> Reviewed-by: Mickaël Salaün <mic@xxxxxxxxxxxxxxxxxxx>
>>
>>>>          free(env_path_name);
>>>>          return ret;
>>>>   }
>>>> -- 
>>>> 2.26.3
>>>>
>>>
>