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Date: Sun, 9 Jan 2022 18:04:45 -0800 From: Andrii Nakryiko <andrii.nakryiko@...il.com> To: Wei Fu <fuweid89@...il.com> Cc: Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>, Martin Lau <kafai@...com>, Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>, john fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>, bpf <bpf@...r.kernel.org>, Networking <netdev@...r.kernel.org>, open list <linux-kernel@...r.kernel.org> Subject: Re: [PATCH bpf] tools/bpf: only set obj->skeleton without err On Sat, Jan 8, 2022 at 12:40 AM Wei Fu <fuweid89@...il.com> 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 ${bpf_app_name}__open. Therefore, we should > set the obj->skeleton before return 0; > > Signed-off-by: Wei Fu <fuweid89@...il.com> > --- > tools/bpf/bpftool/gen.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > Great catch! Added (please add it yourself in the future): Fixes: 5dc7a8b21144 ("bpftool, selftests/bpf: Embed object file inside skeleton") Also reworded the subject a bit. Pushed to bpf-next. > diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c > index 5c18351290f0..e61e08f524da 100644 > --- a/tools/bpf/bpftool/gen.c > +++ b/tools/bpf/bpftool/gen.c > @@ -928,7 +928,6 @@ static int do_skeleton(int argc, char **argv) > s = (struct bpf_object_skeleton *)calloc(1, sizeof(*s));\n\ > if (!s) \n\ > goto err; \n\ > - obj->skeleton = s; \n\ > \n\ > s->sz = sizeof(*s); \n\ > s->name = \"%1$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 >
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