On Thu, Jul 27, 2023 at 9:07 PM Jiri Olsa <olsajiri@xxxxxxxxx> wrote:
>
> On Thu, Jul 27, 2023 at 11:43:08AM +0000, Yafang Shao wrote:
> > The patch 1b715e1b0ec5: "bpf: Support ->fill_link_info for
> > perf_event" from Jul 9, 2023, leads to the following Smatch static
> > checker warning:
> >
> > kernel/bpf/syscall.c:3416 bpf_perf_link_fill_kprobe()
> > error: uninitialized symbol 'type'.
> >
> > That can happens when uname is NULL. So fix it by verifying the uname
> > when we really need to fill it.
> >
> > Fixes: 1b715e1b0ec5 ("bpf: Support ->fill_link_info for perf_event")
> > Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> > Closes: https://lore.kernel.org/bpf/85697a7e-f897-4f74-8b43-82721bebc462@kili.mountain/
> > Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
> > ---
> > kernel/bpf/syscall.c | 10 +++++-----
> > 1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> > index 7f4e8c3..ad9360d 100644
> > --- a/kernel/bpf/syscall.c
> > +++ b/kernel/bpf/syscall.c
> > @@ -3376,16 +3376,16 @@ static int bpf_perf_link_fill_common(const struct perf_event *event,
> > size_t len;
> > int err;
> >
> > - if (!ulen ^ !uname)
> > - return -EINVAL;
>
> would it make more sense to keep above check in place and move the
> !uname change below? I'd think we want to return error in case of
> wrong arguments as soon as possible
Good point. Will change it.
>
> > - if (!uname)
> > - return 0;
> > -
> > err = bpf_get_perf_event_info(event, &prog_id, fd_type, &buf,
> > probe_offset, probe_addr);
> > if (err)
> > return err;
> >
> > + if (!ulen ^ !uname)
> > + return -EINVAL;
> > + if (!uname)
> > + return 0;
>
> and here we just return 0 if we do not store the name to provided buffer
Will do it.
--
Regards
Yafang
