* [PATCH bpf] libbpf: Prevent overriding errno when logging errors
@ 2020-08-13 14:29 Toke Høiland-Jørgensen
2020-08-13 16:41 ` Andrii Nakryiko
0 siblings, 1 reply; 5+ messages in thread
From: Toke Høiland-Jørgensen @ 2020-08-13 14:29 UTC (permalink / raw)
To: Alexei Starovoitov, Daniel Borkmann
Cc: Toke Høiland-Jørgensen, netdev, bpf
Turns out there were a few more instances where libbpf didn't save the
errno before writing an error message, causing errno to be overridden by
the printf() return and the error disappearing if logging is enabled.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
tools/lib/bpf/libbpf.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 0a06124f7999..fd256440e233 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -3478,10 +3478,11 @@ bpf_object__probe_global_data(struct bpf_object *obj)
map = bpf_create_map_xattr(&map_attr);
if (map < 0) {
- cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+ ret = -errno;
+ cp = libbpf_strerror_r(-ret, errmsg, sizeof(errmsg));
pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n",
- __func__, cp, errno);
- return -errno;
+ __func__, cp, -ret);
+ return ret;
}
insns[0].imm = map;
@@ -6012,9 +6013,10 @@ int bpf_program__pin_instance(struct bpf_program *prog, const char *path,
}
if (bpf_obj_pin(prog->instances.fds[instance], path)) {
- cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+ err = -errno;
+ cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
pr_warn("failed to pin program: %s\n", cp);
- return -errno;
+ return err;
}
pr_debug("pinned program '%s'\n", path);
--
2.28.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH bpf] libbpf: Prevent overriding errno when logging errors
2020-08-13 14:29 [PATCH bpf] libbpf: Prevent overriding errno when logging errors Toke Høiland-Jørgensen
@ 2020-08-13 16:41 ` Andrii Nakryiko
2020-08-13 19:52 ` Toke Høiland-Jørgensen
0 siblings, 1 reply; 5+ messages in thread
From: Andrii Nakryiko @ 2020-08-13 16:41 UTC (permalink / raw)
To: Toke Høiland-Jørgensen
Cc: Alexei Starovoitov, Daniel Borkmann, Networking, bpf
On Thu, Aug 13, 2020 at 7:29 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>
> Turns out there were a few more instances where libbpf didn't save the
> errno before writing an error message, causing errno to be overridden by
> the printf() return and the error disappearing if logging is enabled.
>
> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
> ---
Acked-by: Andrii Nakryiko <andriin@fb.com>
> tools/lib/bpf/libbpf.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 0a06124f7999..fd256440e233 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -3478,10 +3478,11 @@ bpf_object__probe_global_data(struct bpf_object *obj)
>
> map = bpf_create_map_xattr(&map_attr);
> if (map < 0) {
> - cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
> + ret = -errno;
> + cp = libbpf_strerror_r(-ret, errmsg, sizeof(errmsg));
fyi, libbpf_strerror_r() is smart enough to work with both negative
and positive error numbers (it basically takes abs(err)), so no need
to ensure it's positive here and below.
> pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n",
> - __func__, cp, errno);
> - return -errno;
> + __func__, cp, -ret);
> + return ret;
> }
>
> insns[0].imm = map;
> @@ -6012,9 +6013,10 @@ int bpf_program__pin_instance(struct bpf_program *prog, const char *path,
> }
>
> if (bpf_obj_pin(prog->instances.fds[instance], path)) {
> - cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
> + err = -errno;
> + cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
> pr_warn("failed to pin program: %s\n", cp);
> - return -errno;
> + return err;
> }
> pr_debug("pinned program '%s'\n", path);
>
> --
> 2.28.0
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH bpf] libbpf: Prevent overriding errno when logging errors
2020-08-13 16:41 ` Andrii Nakryiko
@ 2020-08-13 19:52 ` Toke Høiland-Jørgensen
2020-08-13 20:35 ` Daniel Borkmann
0 siblings, 1 reply; 5+ messages in thread
From: Toke Høiland-Jørgensen @ 2020-08-13 19:52 UTC (permalink / raw)
To: Andrii Nakryiko; +Cc: Alexei Starovoitov, Daniel Borkmann, Networking, bpf
Andrii Nakryiko <andrii.nakryiko@gmail.com> writes:
> On Thu, Aug 13, 2020 at 7:29 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>>
>> Turns out there were a few more instances where libbpf didn't save the
>> errno before writing an error message, causing errno to be overridden by
>> the printf() return and the error disappearing if logging is enabled.
>>
>> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
>> ---
>
> Acked-by: Andrii Nakryiko <andriin@fb.com>
>
>> tools/lib/bpf/libbpf.c | 12 +++++++-----
>> 1 file changed, 7 insertions(+), 5 deletions(-)
>>
>> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
>> index 0a06124f7999..fd256440e233 100644
>> --- a/tools/lib/bpf/libbpf.c
>> +++ b/tools/lib/bpf/libbpf.c
>> @@ -3478,10 +3478,11 @@ bpf_object__probe_global_data(struct bpf_object *obj)
>>
>> map = bpf_create_map_xattr(&map_attr);
>> if (map < 0) {
>> - cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
>> + ret = -errno;
>> + cp = libbpf_strerror_r(-ret, errmsg, sizeof(errmsg));
>
> fyi, libbpf_strerror_r() is smart enough to work with both negative
> and positive error numbers (it basically takes abs(err)), so no need
> to ensure it's positive here and below.
Noted. Although that also means it doesn't hurt either, I suppose; so
not going to bother respinning this unless someone insists :)
-Toke
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH bpf] libbpf: Prevent overriding errno when logging errors
2020-08-13 19:52 ` Toke Høiland-Jørgensen
@ 2020-08-13 20:35 ` Daniel Borkmann
2020-08-13 20:52 ` Toke Høiland-Jørgensen
0 siblings, 1 reply; 5+ messages in thread
From: Daniel Borkmann @ 2020-08-13 20:35 UTC (permalink / raw)
To: Toke Høiland-Jørgensen, Andrii Nakryiko
Cc: Alexei Starovoitov, Networking, bpf
On 8/13/20 9:52 PM, Toke Høiland-Jørgensen wrote:
> Andrii Nakryiko <andrii.nakryiko@gmail.com> writes:
>> On Thu, Aug 13, 2020 at 7:29 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>>>
>>> Turns out there were a few more instances where libbpf didn't save the
>>> errno before writing an error message, causing errno to be overridden by
>>> the printf() return and the error disappearing if logging is enabled.
>>>
>>> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
>>> ---
>>
>> Acked-by: Andrii Nakryiko <andriin@fb.com>
>>
>>> tools/lib/bpf/libbpf.c | 12 +++++++-----
>>> 1 file changed, 7 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
>>> index 0a06124f7999..fd256440e233 100644
>>> --- a/tools/lib/bpf/libbpf.c
>>> +++ b/tools/lib/bpf/libbpf.c
>>> @@ -3478,10 +3478,11 @@ bpf_object__probe_global_data(struct bpf_object *obj)
>>>
>>> map = bpf_create_map_xattr(&map_attr);
>>> if (map < 0) {
>>> - cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
>>> + ret = -errno;
>>> + cp = libbpf_strerror_r(-ret, errmsg, sizeof(errmsg));
>>
>> fyi, libbpf_strerror_r() is smart enough to work with both negative
>> and positive error numbers (it basically takes abs(err)), so no need
>> to ensure it's positive here and below.
>
> Noted. Although that also means it doesn't hurt either, I suppose; so
> not going to bother respinning this unless someone insists :)
Fixed up while applying, thanks!
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH bpf] libbpf: Prevent overriding errno when logging errors
2020-08-13 20:35 ` Daniel Borkmann
@ 2020-08-13 20:52 ` Toke Høiland-Jørgensen
0 siblings, 0 replies; 5+ messages in thread
From: Toke Høiland-Jørgensen @ 2020-08-13 20:52 UTC (permalink / raw)
To: Daniel Borkmann, Andrii Nakryiko; +Cc: Alexei Starovoitov, Networking, bpf
Daniel Borkmann <daniel@iogearbox.net> writes:
> On 8/13/20 9:52 PM, Toke Høiland-Jørgensen wrote:
>> Andrii Nakryiko <andrii.nakryiko@gmail.com> writes:
>>> On Thu, Aug 13, 2020 at 7:29 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>>>>
>>>> Turns out there were a few more instances where libbpf didn't save the
>>>> errno before writing an error message, causing errno to be overridden by
>>>> the printf() return and the error disappearing if logging is enabled.
>>>>
>>>> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
>>>> ---
>>>
>>> Acked-by: Andrii Nakryiko <andriin@fb.com>
>>>
>>>> tools/lib/bpf/libbpf.c | 12 +++++++-----
>>>> 1 file changed, 7 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
>>>> index 0a06124f7999..fd256440e233 100644
>>>> --- a/tools/lib/bpf/libbpf.c
>>>> +++ b/tools/lib/bpf/libbpf.c
>>>> @@ -3478,10 +3478,11 @@ bpf_object__probe_global_data(struct bpf_object *obj)
>>>>
>>>> map = bpf_create_map_xattr(&map_attr);
>>>> if (map < 0) {
>>>> - cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
>>>> + ret = -errno;
>>>> + cp = libbpf_strerror_r(-ret, errmsg, sizeof(errmsg));
>>>
>>> fyi, libbpf_strerror_r() is smart enough to work with both negative
>>> and positive error numbers (it basically takes abs(err)), so no need
>>> to ensure it's positive here and below.
>>
>> Noted. Although that also means it doesn't hurt either, I suppose; so
>> not going to bother respinning this unless someone insists :)
>
> Fixed up while applying, thanks!
Great, thanks!
-Toke
^ permalink raw reply [flat|nested] 5+ messages in thread
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2020-08-13 14:29 [PATCH bpf] libbpf: Prevent overriding errno when logging errors Toke Høiland-Jørgensen
2020-08-13 16:41 ` Andrii Nakryiko
2020-08-13 19:52 ` Toke Høiland-Jørgensen
2020-08-13 20:35 ` Daniel Borkmann
2020-08-13 20:52 ` Toke Høiland-Jørgensen
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