On Sun, 26 May 2024 14:27:56 +0200
Carlos López <clo...@suse.de> wrote:
>
> Hi,
>
> On 26/5/24 12:17, Masami Hiramatsu (Google) wrote:
> > On Sat, 25 May 2024 20:21:32 +0200
> > Carlos López <clo...@suse.de> wrote:
> >
> >> btf_find_struct_member() might return NULL or an error via the
> >> ERR_PTR() macro. However, its caller in parse_btf_field() only checks
> >> for the NULL condition. Fix this by using IS_ERR() and returning the
> >> error up the stack.
> >>
> >
> > Thanks for finding it!
> > I think this requires new error message for error_log file.
> > Can you add the log as
> >
> > trace_probe_log_err(ctx->offset, BTF_ERROR);
> >
> > And define BTF_ERROR in ERRORS@kernel/trace/trace_probe.h ?
>
> Sounds good, but should we perhaps reuse BAD_BTF_TID?
>
> ```
> C(BAD_BTF_TID, "Failed to get BTF type info."),\
> ```
>
> `btf_find_struct_member()` fails if `type` is not a struct or if it runs
> OOM while allocating the anon stack, so it seems appropriate.
Good point, it sounds reasonable.
Thanks!
>
> Best,
> Carlos
>
> > Thank you,
> >
> >> Fixes: c440adfbe3025 ("tracing/probes: Support BTF based data structure
> >> field access")
> >> Signed-off-by: Carlos López <clo...@suse.de>
> >> ---
> >> kernel/trace/trace_probe.c | 2 ++
> >> 1 file changed, 2 insertions(+)
> >>
> >> diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> >> index 5e263c141574..5417e9712157 100644
> >> --- a/kernel/trace/trace_probe.c
> >> +++ b/kernel/trace/trace_probe.c
> >> @@ -554,6 +554,8 @@ static int parse_btf_field(char *fieldname, const
> >> struct btf_type *type,
> >> anon_offs = 0;
> >> field = btf_find_struct_member(ctx->btf, type,
> >> fieldname,
> >> &anon_offs);
> >> + if (IS_ERR(field))
> >> + return PTR_ERR(field);
> >> if (!field) {
> >> trace_probe_log_err(ctx->offset, NO_BTF_FIELD);
> >> return -ENOENT;
> >> --
> >> 2.35.3
> >>
> >
> >
>
> --
> Carlos López
> Security Engineer
> SUSE Software Solutions
--
Masami Hiramatsu (Google) <mhira...@kernel.org>
