* [PATCH bpf] tools/bpf: only set obj->skeleton without err
@ 2022-01-08 8:40 Wei Fu
2022-01-10 2:04 ` Andrii Nakryiko
0 siblings, 1 reply; 3+ messages in thread
From: Wei Fu @ 2022-01-08 8:40 UTC (permalink / raw)
To: ast, daniel, andrii, kafai, songliubraving, yhs, john.fastabend,
kpsingh
Cc: bpf, netdev, linux-kernel, Wei Fu
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 ${bpf_app_name}__open. Therefore, we should
set the obj->skeleton before return 0;
Signed-off-by: Wei Fu <fuweid89@gmail.com>
---
tools/bpf/bpftool/gen.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
index 5c18351290f0..e61e08f524da 100644
--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -928,7 +928,6 @@ static int do_skeleton(int argc, char **argv)
s = (struct bpf_object_skeleton *)calloc(1, sizeof(*s));\n\
if (!s) \n\
goto err; \n\
- obj->skeleton = s; \n\
\n\
s->sz = sizeof(*s); \n\
s->name = \"%1$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
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH bpf] tools/bpf: only set obj->skeleton without err
2022-01-08 8:40 [PATCH bpf] tools/bpf: only set obj->skeleton without err Wei Fu
@ 2022-01-10 2:04 ` Andrii Nakryiko
2022-01-11 17:09 ` Wei Fu
0 siblings, 1 reply; 3+ messages in thread
From: Andrii Nakryiko @ 2022-01-10 2:04 UTC (permalink / raw)
To: Wei Fu
Cc: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Martin Lau,
Song Liu, Yonghong Song, john fastabend, KP Singh, bpf,
Networking, open list
On Sat, Jan 8, 2022 at 12:40 AM Wei Fu <fuweid89@gmail.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 ${bpf_app_name}__open. Therefore, we should
> set the obj->skeleton before return 0;
>
> Signed-off-by: Wei Fu <fuweid89@gmail.com>
> ---
> tools/bpf/bpftool/gen.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
Great catch! Added (please add it yourself in the future):
Fixes: 5dc7a8b21144 ("bpftool, selftests/bpf: Embed object file inside
skeleton")
Also reworded the subject a bit. Pushed to bpf-next.
> diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
> index 5c18351290f0..e61e08f524da 100644
> --- a/tools/bpf/bpftool/gen.c
> +++ b/tools/bpf/bpftool/gen.c
> @@ -928,7 +928,6 @@ static int do_skeleton(int argc, char **argv)
> s = (struct bpf_object_skeleton *)calloc(1, sizeof(*s));\n\
> if (!s) \n\
> goto err; \n\
> - obj->skeleton = s; \n\
> \n\
> s->sz = sizeof(*s); \n\
> s->name = \"%1$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
>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH bpf] tools/bpf: only set obj->skeleton without err
2022-01-10 2:04 ` Andrii Nakryiko
@ 2022-01-11 17:09 ` Wei Fu
0 siblings, 0 replies; 3+ messages in thread
From: Wei Fu @ 2022-01-11 17:09 UTC (permalink / raw)
To: Andrii Nakryiko
Cc: andrii, ast, bpf, daniel, john.fastabend, kafai, kpsingh,
linux-kernel, netdev, songliubraving, yhs, fuweid89
On Sun, Jan 09, 2022 at 06:04:45PM -0800, Andrii Nakryiko wrote:
> On Sat, Jan 8, 2022 at 12:40 AM Wei Fu <fuweid89@gmail.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@gmail.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.
Sure! Thanks for the review.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-01-08 8:40 [PATCH bpf] tools/bpf: only set obj->skeleton without err Wei Fu
2022-01-10 2:04 ` Andrii Nakryiko
2022-01-11 17:09 ` Wei Fu
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