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

[Tom Rix]

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 ?

Tom

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