* [PATCH bpf-next] selftests/bpf: fix crash in core_reloc when bpftool btfgen fails
@ 2022-02-17 18:02 Yucong Sun
2022-02-17 18:32 ` Martin KaFai Lau
2022-02-17 19:10 ` patchwork-bot+netdevbpf
0 siblings, 2 replies; 6+ messages in thread
From: Yucong Sun @ 2022-02-17 18:02 UTC (permalink / raw)
To: bpf; +Cc: andrii, fallentree, sunyucong
Initialize obj to null and skip closing if null.
Signed-off-by: Yucong Sun <fallentree@fb.com>
---
tools/testing/selftests/bpf/prog_tests/core_reloc.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/core_reloc.c b/tools/testing/selftests/bpf/prog_tests/core_reloc.c
index baf53c23c08d..7211243a22c3 100644
--- a/tools/testing/selftests/bpf/prog_tests/core_reloc.c
+++ b/tools/testing/selftests/bpf/prog_tests/core_reloc.c
@@ -861,7 +861,7 @@ static void run_core_reloc_tests(bool use_btfgen)
struct bpf_link *link = NULL;
struct bpf_map *data_map;
struct bpf_program *prog;
- struct bpf_object *obj;
+ struct bpf_object *obj = NULL;
uint64_t my_pid_tgid;
struct data *data;
void *mmap_data = NULL;
@@ -992,7 +992,8 @@ static void run_core_reloc_tests(bool use_btfgen)
remove(btf_file);
bpf_link__destroy(link);
link = NULL;
- bpf_object__close(obj);
+ if (obj)
+ bpf_object__close(obj);
}
}
--
2.30.2
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: fix crash in core_reloc when bpftool btfgen fails
2022-02-17 18:02 [PATCH bpf-next] selftests/bpf: fix crash in core_reloc when bpftool btfgen fails Yucong Sun
@ 2022-02-17 18:32 ` Martin KaFai Lau
2022-02-17 18:55 ` sunyucong
2022-02-17 19:10 ` patchwork-bot+netdevbpf
1 sibling, 1 reply; 6+ messages in thread
From: Martin KaFai Lau @ 2022-02-17 18:32 UTC (permalink / raw)
To: Yucong Sun; +Cc: bpf, andrii, sunyucong
On Thu, Feb 17, 2022 at 10:02:10AM -0800, Yucong Sun wrote:
> Initialize obj to null and skip closing if null.
>
> Signed-off-by: Yucong Sun <fallentree@fb.com>
> ---
> tools/testing/selftests/bpf/prog_tests/core_reloc.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/core_reloc.c b/tools/testing/selftests/bpf/prog_tests/core_reloc.c
> index baf53c23c08d..7211243a22c3 100644
> --- a/tools/testing/selftests/bpf/prog_tests/core_reloc.c
> +++ b/tools/testing/selftests/bpf/prog_tests/core_reloc.c
> @@ -861,7 +861,7 @@ static void run_core_reloc_tests(bool use_btfgen)
> struct bpf_link *link = NULL;
> struct bpf_map *data_map;
> struct bpf_program *prog;
> - struct bpf_object *obj;
> + struct bpf_object *obj = NULL;
> uint64_t my_pid_tgid;
> struct data *data;
> void *mmap_data = NULL;
> @@ -992,7 +992,8 @@ static void run_core_reloc_tests(bool use_btfgen)
> remove(btf_file);
> bpf_link__destroy(link);
> link = NULL;
> - bpf_object__close(obj);
> + if (obj)
> + bpf_object__close(obj);
Should it be:
bpf_object__close(obj);
obj = NULL:
> }
> }
>
> --
> 2.30.2
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: fix crash in core_reloc when bpftool btfgen fails
2022-02-17 18:32 ` Martin KaFai Lau
@ 2022-02-17 18:55 ` sunyucong
2022-02-17 18:57 ` Andrii Nakryiko
0 siblings, 1 reply; 6+ messages in thread
From: sunyucong @ 2022-02-17 18:55 UTC (permalink / raw)
To: Martin KaFai Lau; +Cc: Yucong Sun, bpf, Andrii Nakryiko
> Should it be:
> bpf_object__close(obj);
> obj = NULL:
No, the actual crash is caused by this line:
https://github.com/kernel-patches/bpf/blob/bpf-next/tools/testing/selftests/bpf/prog_tests/core_reloc.c#L896
When run_btfgen fails, the obj contains uninitialized data and then
bpf_object__close(obj) crashes.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: fix crash in core_reloc when bpftool btfgen fails
2022-02-17 18:55 ` sunyucong
@ 2022-02-17 18:57 ` Andrii Nakryiko
2022-02-17 19:07 ` Andrii Nakryiko
0 siblings, 1 reply; 6+ messages in thread
From: Andrii Nakryiko @ 2022-02-17 18:57 UTC (permalink / raw)
To: sunyucong@gmail.com; +Cc: Martin KaFai Lau, Yucong Sun, bpf, Andrii Nakryiko
On Thu, Feb 17, 2022 at 10:55 AM sunyucong@gmail.com
<sunyucong@gmail.com> wrote:
>
> > Should it be:
> > bpf_object__close(obj);
> > obj = NULL:
>
> No, the actual crash is caused by this line:
> https://github.com/kernel-patches/bpf/blob/bpf-next/tools/testing/selftests/bpf/prog_tests/core_reloc.c#L896
>
> When run_btfgen fails, the obj contains uninitialized data and then
> bpf_object__close(obj) crashes.
Martin's point is that you have to NULL out obj so that on the next
iteration this doesn't crash again. I'll fix it up while applying.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: fix crash in core_reloc when bpftool btfgen fails
2022-02-17 18:57 ` Andrii Nakryiko
@ 2022-02-17 19:07 ` Andrii Nakryiko
0 siblings, 0 replies; 6+ messages in thread
From: Andrii Nakryiko @ 2022-02-17 19:07 UTC (permalink / raw)
To: sunyucong@gmail.com; +Cc: Martin KaFai Lau, Yucong Sun, bpf, Andrii Nakryiko
On Thu, Feb 17, 2022 at 10:57 AM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Thu, Feb 17, 2022 at 10:55 AM sunyucong@gmail.com
> <sunyucong@gmail.com> wrote:
> >
> > > Should it be:
> > > bpf_object__close(obj);
> > > obj = NULL:
> >
> > No, the actual crash is caused by this line:
> > https://github.com/kernel-patches/bpf/blob/bpf-next/tools/testing/selftests/bpf/prog_tests/core_reloc.c#L896
> >
> > When run_btfgen fails, the obj contains uninitialized data and then
> > bpf_object__close(obj) crashes.
>
>
> Martin's point is that you have to NULL out obj so that on the next
> iteration this doesn't crash again. I'll fix it up while applying.
But I actually ended up replacing two goto cleanup with continue
(there is no clean up to do). And adjusted commit message to reflect
that. Applied to bpf-next, thanks for the fix!
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: fix crash in core_reloc when bpftool btfgen fails
2022-02-17 18:02 [PATCH bpf-next] selftests/bpf: fix crash in core_reloc when bpftool btfgen fails Yucong Sun
2022-02-17 18:32 ` Martin KaFai Lau
@ 2022-02-17 19:10 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 6+ messages in thread
From: patchwork-bot+netdevbpf @ 2022-02-17 19:10 UTC (permalink / raw)
To: Yucong Sun; +Cc: bpf, andrii, sunyucong
Hello:
This patch was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <andrii@kernel.org>:
On Thu, 17 Feb 2022 10:02:10 -0800 you wrote:
> Initialize obj to null and skip closing if null.
>
> Signed-off-by: Yucong Sun <fallentree@fb.com>
> ---
> tools/testing/selftests/bpf/prog_tests/core_reloc.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
Here is the summary with links:
- [bpf-next] selftests/bpf: fix crash in core_reloc when bpftool btfgen fails
https://git.kernel.org/bpf/bpf-next/c/b75dacaac465
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
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^ permalink raw reply [flat|nested] 6+ messages in thread
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2022-02-17 18:02 [PATCH bpf-next] selftests/bpf: fix crash in core_reloc when bpftool btfgen fails Yucong Sun
2022-02-17 18:32 ` Martin KaFai Lau
2022-02-17 18:55 ` sunyucong
2022-02-17 18:57 ` Andrii Nakryiko
2022-02-17 19:07 ` Andrii Nakryiko
2022-02-17 19:10 ` patchwork-bot+netdevbpf
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