[PATCH bpf-next] tools/bpf: fix a selftest test_btf failure

[PATCH bpf-next] tools/bpf: fix a selftest test_btf failure

[Yonghong Song]

Commit 9c651127445c ("selftests/btf: add initial BTF dedup tests")
added dedup tests in test_btf.c.
It broke the raw test:
 BTF raw test[71] (func proto (Bad arg name_off)):
    btf_raw_create:2905:FAIL Error getting string #65535, strs_cnt:1

The test itself encodes invalid func_proto parameter name
offset 0xffffFFFF as a negative test for the kernel.
The above commit changed the meaning of that offset and
resulted in a user space error.
  #define NAME_NTH(N) (0xffff0000 | N)
  #define IS_NAME_NTH(X) ((X & 0xffff0000) == 0xffff0000)
  #define GET_NAME_NTH_IDX(X) (X & 0x0000ffff)

Currently, the kernel permits maximum name offset 0xffff.
Set the test name off as 0x0fffFFFF to trigger the kernel
verification failure.

Cc: Andrii Nakryiko <andriin@fb.com>
Fixes: 9c651127445c ("selftests/btf: add initial BTF dedup tests")
Signed-off-by: Yonghong Song <yhs@fb.com>
---
 tools/testing/selftests/bpf/test_btf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/test_btf.c b/tools/testing/selftests/bpf/test_btf.c
index 30c3edde7e07..447acc34db94 100644
--- a/tools/testing/selftests/bpf/test_btf.c
+++ b/tools/testing/selftests/bpf/test_btf.c
@@ -1978,7 +1978,7 @@ static struct btf_raw_test raw_tests[] = {
 		/* void (*)(int a, unsigned int <bad_name_off>) */
 		BTF_FUNC_PROTO_ENC(0, 2),			/* [3] */
 			BTF_FUNC_PROTO_ARG_ENC(NAME_TBD, 1),
-			BTF_FUNC_PROTO_ARG_ENC(0xffffffff, 2),
+			BTF_FUNC_PROTO_ARG_ENC(0x0fffffff, 2),
 		BTF_END_RAW,
 	},
 	.str_sec = "\0a",
-- 
2.17.1

Re: [PATCH bpf-next] tools/bpf: fix a selftest test_btf failure

[Andrii Nakryiko]

On Tue, Feb 5, 2019 at 2:30 PM Yonghong Song <yhs@fb.com> wrote:
>
> Commit 9c651127445c ("selftests/btf: add initial BTF dedup tests")
> added dedup tests in test_btf.c.
> It broke the raw test:
>  BTF raw test[71] (func proto (Bad arg name_off)):
>     btf_raw_create:2905:FAIL Error getting string #65535, strs_cnt:1

Argh.. Thanks for fixing this!

>
> The test itself encodes invalid func_proto parameter name
> offset 0xffffFFFF as a negative test for the kernel.
> The above commit changed the meaning of that offset and
> resulted in a user space error.
>   #define NAME_NTH(N) (0xffff0000 | N)
>   #define IS_NAME_NTH(X) ((X & 0xffff0000) == 0xffff0000)
>   #define GET_NAME_NTH_IDX(X) (X & 0x0000ffff)
>
> Currently, the kernel permits maximum name offset 0xffff.
> Set the test name off as 0x0fffFFFF to trigger the kernel
> verification failure.
>
> Cc: Andrii Nakryiko <andriin@fb.com>
> Fixes: 9c651127445c ("selftests/btf: add initial BTF dedup tests")
> Signed-off-by: Yonghong Song <yhs@fb.com>
> ---
>  tools/testing/selftests/bpf/test_btf.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/bpf/test_btf.c b/tools/testing/selftests/bpf/test_btf.c
> index 30c3edde7e07..447acc34db94 100644
> --- a/tools/testing/selftests/bpf/test_btf.c
> +++ b/tools/testing/selftests/bpf/test_btf.c
> @@ -1978,7 +1978,7 @@ static struct btf_raw_test raw_tests[] = {
>                 /* void (*)(int a, unsigned int <bad_name_off>) */
>                 BTF_FUNC_PROTO_ENC(0, 2),                       /* [3] */
>                         BTF_FUNC_PROTO_ARG_ENC(NAME_TBD, 1),
> -                       BTF_FUNC_PROTO_ARG_ENC(0xffffffff, 2),
> +                       BTF_FUNC_PROTO_ARG_ENC(0x0fffffff, 2),
>                 BTF_END_RAW,
>         },
>         .str_sec = "\0a",
> --
> 2.17.1
>

Acked-by: Andrii Nakryiko <andriin@fb.com>

Re: [PATCH bpf-next] tools/bpf: fix a selftest test_btf failure

[Alexei Starovoitov]

On Tue, Feb 05, 2019 at 02:28:44PM -0800, Yonghong Song wrote:
> Commit 9c651127445c ("selftests/btf: add initial BTF dedup tests")
> added dedup tests in test_btf.c.
> It broke the raw test:
>  BTF raw test[71] (func proto (Bad arg name_off)):
>     btf_raw_create:2905:FAIL Error getting string #65535, strs_cnt:1
> 
> The test itself encodes invalid func_proto parameter name
> offset 0xffffFFFF as a negative test for the kernel.
> The above commit changed the meaning of that offset and
> resulted in a user space error.
>   #define NAME_NTH(N) (0xffff0000 | N)
>   #define IS_NAME_NTH(X) ((X & 0xffff0000) == 0xffff0000)
>   #define GET_NAME_NTH_IDX(X) (X & 0x0000ffff)
> 
> Currently, the kernel permits maximum name offset 0xffff.
> Set the test name off as 0x0fffFFFF to trigger the kernel
> verification failure.
> 
> Cc: Andrii Nakryiko <andriin@fb.com>
> Fixes: 9c651127445c ("selftests/btf: add initial BTF dedup tests")
> Signed-off-by: Yonghong Song <yhs@fb.com>

Applied, Thanks

Also I see the following new error in test_btf:
BTF libbpf test[2] (test_btf_nokv.o): libbpf: map:btf_map container_name:____btf_map_btf_map cannot be found in BTF. Missing BPF_ANNOTATE_KV_PAIR?
OK

A bunch of similar errors are in test_progs as well.
I suspect it's related to the last few btf changes.
Andrii, Yonghong, Please investigate.

Re: [PATCH bpf-next] tools/bpf: fix a selftest test_btf failure

[Yonghong Song]

On 2/5/19 6:36 PM, Alexei Starovoitov wrote:
> On Tue, Feb 05, 2019 at 02:28:44PM -0800, Yonghong Song wrote:
>> Commit 9c651127445c ("selftests/btf: add initial BTF dedup tests")
>> added dedup tests in test_btf.c.
>> It broke the raw test:
>>   BTF raw test[71] (func proto (Bad arg name_off)):
>>      btf_raw_create:2905:FAIL Error getting string #65535, strs_cnt:1
>>
>> The test itself encodes invalid func_proto parameter name
>> offset 0xffffFFFF as a negative test for the kernel.
>> The above commit changed the meaning of that offset and
>> resulted in a user space error.
>>    #define NAME_NTH(N) (0xffff0000 | N)
>>    #define IS_NAME_NTH(X) ((X & 0xffff0000) == 0xffff0000)
>>    #define GET_NAME_NTH_IDX(X) (X & 0x0000ffff)
>>
>> Currently, the kernel permits maximum name offset 0xffff.
>> Set the test name off as 0x0fffFFFF to trigger the kernel
>> verification failure.
>>
>> Cc: Andrii Nakryiko <andriin@fb.com>
>> Fixes: 9c651127445c ("selftests/btf: add initial BTF dedup tests")
>> Signed-off-by: Yonghong Song <yhs@fb.com>
> 
> Applied, Thanks
> 
> Also I see the following new error in test_btf:
> BTF libbpf test[2] (test_btf_nokv.o): libbpf: map:btf_map container_name:____btf_map_btf_map cannot be found in BTF. Missing BPF_ANNOTATE_KV_PAIR?
> OK
> 
> A bunch of similar errors are in test_progs as well.
> I suspect it's related to the last few btf changes.
> Andrii, Yonghong, Please investigate.

It is due to one of previous patches to refector btf__get_map_kv_tids(),
accidentally using pr_warning instead of original pr_debug.
Will submit a patch soon.

>