On Sat, Jan 8, 2022 at 12:40 AM Wei Fu <fuweid89@xxxxxxxxx> wrote:
>
> After `bpftool gen skeleton`, the ${bpf_app}.skel.h will provide that
> ${bpf_app_name}__open helper to load bpf. If there is some error
> like ENOMEM, the ${bpf_app_name}__open will rollback(free) the allocated
> object, including `bpf_object_skeleton`.
>
> Since the ${bpf_app_name}__create_skeleton set the obj->skeleton first
> and not rollback it when error, it will cause double-free in
> ${bpf_app_name}__destory at ${bpf_app_name}__open. Therefore, we should
> set the obj->skeleton before return 0;
>
> Signed-off-by: Wei Fu <fuweid89@xxxxxxxxx>
> ---
> tools/bpf/bpftool/gen.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
Great catch! Added (please add it yourself in the future):
Fixes: 5dc7a8b21144 ("bpftool, selftests/bpf: Embed object file inside
skeleton")
Also reworded the subject a bit. Pushed to bpf-next.
> diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
> index 5c18351290f0..e61e08f524da 100644
> --- a/tools/bpf/bpftool/gen.c
> +++ b/tools/bpf/bpftool/gen.c
> @@ -928,7 +928,6 @@ static int do_skeleton(int argc, char **argv)
> s = (struct bpf_object_skeleton *)calloc(1, sizeof(*s));\n\
> if (!s) \n\
> goto err; \n\
> - obj->skeleton = s; \n\
> \n\
> s->sz = sizeof(*s); \n\
> s->name = \"%1$s\"; \n\
> @@ -1001,6 +1000,8 @@ static int do_skeleton(int argc, char **argv)
> \n\
> s->data = (void *)%2$s__elf_bytes(&s->data_sz); \n\
> \n\
> + obj->skeleton = s; \n\
> + \n\
> return 0; \n\
> err: \n\
> bpf_object__destroy_skeleton(s); \n\
> --
> 2.25.1
>
