[v2] clang-tools support in tools

[PATCH v2 10/18] perf dlfilter: Be defensive against potential NULL dereference

Posted by Ian Rogers 2 years, 2 months ago

In the unlikely case of having a symbol without a mapping, avoid a
NULL dereference that clang-tidy warns about.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/dlfilter.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/dlfilter.c b/tools/perf/util/dlfilter.c
index 1dbf27822ee2..5e54832137a9 100644
--- a/tools/perf/util/dlfilter.c
+++ b/tools/perf/util/dlfilter.c
@@ -52,8 +52,10 @@ static void al_to_d_al(struct addr_location *al, struct perf_dlfilter_al *d_al)
 		d_al->sym_end = sym->end;
 		if (al->addr < sym->end)
 			d_al->symoff = al->addr - sym->start;
-		else
+		else if (al->map)
 			d_al->symoff = al->addr - map__start(al->map) - sym->start;
+		else
+			d_al->symoff = 0;
 		d_al->sym_binding = sym->binding;
 	} else {
 		d_al->sym = NULL;
-- 
2.42.0.609.gbb76f46606-goog

Re: [PATCH v2 10/18] perf dlfilter: Be defensive against potential NULL dereference

Posted by Namhyung Kim 2 years, 2 months ago

On Thu, Oct 5, 2023 at 4:09 PM Ian Rogers <irogers@google.com> wrote:
>
> In the unlikely case of having a symbol without a mapping, avoid a
> NULL dereference that clang-tidy warns about.

I'm not sure if it's possible to have a symbol without a map,
but I'm also fine with being conservative.

Thanks,
Namhyung

>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/perf/util/dlfilter.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/dlfilter.c b/tools/perf/util/dlfilter.c
> index 1dbf27822ee2..5e54832137a9 100644
> --- a/tools/perf/util/dlfilter.c
> +++ b/tools/perf/util/dlfilter.c
> @@ -52,8 +52,10 @@ static void al_to_d_al(struct addr_location *al, struct perf_dlfilter_al *d_al)
>                 d_al->sym_end = sym->end;
>                 if (al->addr < sym->end)
>                         d_al->symoff = al->addr - sym->start;
> -               else
> +               else if (al->map)
>                         d_al->symoff = al->addr - map__start(al->map) - sym->start;
> +               else
> +                       d_al->symoff = 0;
>                 d_al->sym_binding = sym->binding;
>         } else {
>                 d_al->sym = NULL;
> --
> 2.42.0.609.gbb76f46606-goog
>