Re: [PATCH] tracing/probes: fix error check in parse_btf_field()
On Sun, 26 May 2024 14:27:56 +0200
Carlos López wrote:
>
> Hi,
>
> On 26/5/24 12:17, Masami Hiramatsu (Google) wrote:
> > On Sat, 25 May 2024 20:21:32 +0200
> > Carlos López wrote:
> >
> >> btf_find_struct_member() might return NULL or an error via the
> >> ERR_PTR() macro. However, its caller in parse_btf_field() only checks
> >> for the NULL condition. Fix this by using IS_ERR() and returning the
> >> error up the stack.
> >>
> >
> > Thanks for finding it!
> > I think this requires new error message for error_log file.
> > Can you add the log as
> >
> > trace_probe_log_err(ctx->offset, BTF_ERROR);
> >
> > And define BTF_ERROR in ERRORS@kernel/trace/trace_probe.h ?
>
> Sounds good, but should we perhaps reuse BAD_BTF_TID?
>
> ```
> C(BAD_BTF_TID,"Failed to get BTF type info."),\
> ```
>
> `btf_find_struct_member()` fails if `type` is not a struct or if it runs
> OOM while allocating the anon stack, so it seems appropriate.
Good point, it sounds reasonable.
Thanks!
>
> Best,
> Carlos
>
> > Thank you,
> >
> >> Fixes: c440adfbe3025 ("tracing/probes: Support BTF based data structure
> >> field access")
> >> Signed-off-by: Carlos López
> >> ---
> >> kernel/trace/trace_probe.c | 2 ++
> >> 1 file changed, 2 insertions(+)
> >>
> >> diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> >> index 5e263c141574..5417e9712157 100644
> >> --- a/kernel/trace/trace_probe.c
> >> +++ b/kernel/trace/trace_probe.c
> >> @@ -554,6 +554,8 @@ static int parse_btf_field(char *fieldname, const
> >> struct btf_type *type,
> >>anon_offs = 0;
> >>field = btf_find_struct_member(ctx->btf, type,
> >> fieldname,
> >> _offs);
> >> + if (IS_ERR(field))
> >> + return PTR_ERR(field);
> >>if (!field) {
> >>trace_probe_log_err(ctx->offset, NO_BTF_FIELD);
> >>return -ENOENT;
> >> --
> >> 2.35.3
> >>
> >
> >
>
> --
> Carlos López
> Security Engineer
> SUSE Software Solutions
--
Masami Hiramatsu (Google)
Re: [PATCH] tracing/probes: fix error check in parse_btf_field()
Hi,
On 26/5/24 12:17, Masami Hiramatsu (Google) wrote:
On Sat, 25 May 2024 20:21:32 +0200
Carlos López wrote:
btf_find_struct_member() might return NULL or an error via the
ERR_PTR() macro. However, its caller in parse_btf_field() only checks
for the NULL condition. Fix this by using IS_ERR() and returning the
error up the stack.
Thanks for finding it!
I think this requires new error message for error_log file.
Can you add the log as
trace_probe_log_err(ctx->offset, BTF_ERROR);
And define BTF_ERROR in ERRORS@kernel/trace/trace_probe.h ?
Sounds good, but should we perhaps reuse BAD_BTF_TID?
```
C(BAD_BTF_TID, "Failed to get BTF type info."),\
```
`btf_find_struct_member()` fails if `type` is not a struct or if it runs
OOM while allocating the anon stack, so it seems appropriate.
Best,
Carlos
Thank you,
Fixes: c440adfbe3025 ("tracing/probes: Support BTF based data structure field
access")
Signed-off-by: Carlos López
---
kernel/trace/trace_probe.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 5e263c141574..5417e9712157 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -554,6 +554,8 @@ static int parse_btf_field(char *fieldname, const struct
btf_type *type,
anon_offs = 0;
field = btf_find_struct_member(ctx->btf, type,
fieldname,
_offs);
+ if (IS_ERR(field))
+ return PTR_ERR(field);
if (!field) {
trace_probe_log_err(ctx->offset, NO_BTF_FIELD);
return -ENOENT;
--
2.35.3
--
Carlos López
Security Engineer
SUSE Software Solutions
Re: [PATCH] tracing/probes: fix error check in parse_btf_field()
On Sat, 25 May 2024 20:21:32 +0200
Carlos López wrote:
> btf_find_struct_member() might return NULL or an error via the
> ERR_PTR() macro. However, its caller in parse_btf_field() only checks
> for the NULL condition. Fix this by using IS_ERR() and returning the
> error up the stack.
>
Thanks for finding it!
I think this requires new error message for error_log file.
Can you add the log as
trace_probe_log_err(ctx->offset, BTF_ERROR);
And define BTF_ERROR in ERRORS@kernel/trace/trace_probe.h ?
Thank you,
> Fixes: c440adfbe3025 ("tracing/probes: Support BTF based data structure field
> access")
> Signed-off-by: Carlos López
> ---
> kernel/trace/trace_probe.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> index 5e263c141574..5417e9712157 100644
> --- a/kernel/trace/trace_probe.c
> +++ b/kernel/trace/trace_probe.c
> @@ -554,6 +554,8 @@ static int parse_btf_field(char *fieldname, const struct
> btf_type *type,
> anon_offs = 0;
> field = btf_find_struct_member(ctx->btf, type,
> fieldname,
> _offs);
> + if (IS_ERR(field))
> + return PTR_ERR(field);
> if (!field) {
> trace_probe_log_err(ctx->offset, NO_BTF_FIELD);
> return -ENOENT;
> --
> 2.35.3
>
--
Masami Hiramatsu (Google)
[PATCH] tracing/probes: fix error check in parse_btf_field()
btf_find_struct_member() might return NULL or an error via the
ERR_PTR() macro. However, its caller in parse_btf_field() only checks
for the NULL condition. Fix this by using IS_ERR() and returning the
error up the stack.
Fixes: c440adfbe3025 ("tracing/probes: Support BTF based data structure field
access")
Signed-off-by: Carlos López
---
kernel/trace/trace_probe.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 5e263c141574..5417e9712157 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -554,6 +554,8 @@ static int parse_btf_field(char *fieldname, const struct
btf_type *type,
anon_offs = 0;
field = btf_find_struct_member(ctx->btf, type,
fieldname,
_offs);
+ if (IS_ERR(field))
+ return PTR_ERR(field);
if (!field) {
trace_probe_log_err(ctx->offset, NO_BTF_FIELD);
return -ENOENT;
--
2.35.3
