Re: [PATCH v7 3/5] perf namespaces: Add reference count checking

[Arnaldo Carvalho de Melo]

Em Fri, Apr 07, 2023 at 04:04:03PM -0700, Ian Rogers escreveu:
> Add reference count checking controlled by REFCNT_CHECKING ifdef. The
> reference count checking interposes an allocated pointer between the
> reference counted struct on a get and frees the pointer on a put.
> Accesses after a put cause faults and use after free, missed puts are
> caughts as leaks and double puts are double frees.
> 
> This checking helped resolve a memory leak and use after free:
> https://lore.kernel.org/linux-perf-users/CAP-5=fWZH20L4kv-BwVtGLwR=Em3AOOT+Q4QGivvQuYn5AsPRg@xxxxxxxxxxxxxx/
> 
> Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
> ---
>  tools/perf/builtin-inject.c  |   2 +-
>  tools/perf/util/annotate.c   |   2 +-
>  tools/perf/util/dso.c        |   2 +-
>  tools/perf/util/dsos.c       |   2 +-
>  tools/perf/util/namespaces.c | 132 ++++++++++++++++++++---------------
>  tools/perf/util/namespaces.h |   3 +-
>  tools/perf/util/symbol.c     |   2 +-
>  7 files changed, 83 insertions(+), 62 deletions(-)
> 
> diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
> index fd2b38458a5d..fe6ddcf7fb1e 100644
> --- a/tools/perf/builtin-inject.c
> +++ b/tools/perf/builtin-inject.c
> @@ -632,7 +632,7 @@ static int dso__read_build_id(struct dso *dso)
>  	else if (dso->nsinfo) {
>  		char *new_name;
>  
> -		new_name = filename_with_chroot(dso->nsinfo->pid,
> +		new_name = filename_with_chroot(RC_CHK_ACCESS(dso->nsinfo)->pid,
>  						dso->long_name);

To reduce these: