diff mbox series

[RFC,1/5] tracing/probes: Fix to search structure fields correctly

Message ID 170791694361.389532.10047514554799419688.stgit@devnote2
State New
Headers
Series tracing/probes: Support function parameter access from return probe |

Commit Message

Masami Hiramatsu (Google) Feb. 14, 2024, 1:22 p.m. UTC 
  From: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Fix to search a field from the structure which has anonymous union
correctly.
Since the reference `type` pointer was updated in the loop, the search
loop suddenly aborted where it hits an anonymous union. Thus it can not
find the field after the anonymous union. This avoids updating the
cursor `type` pointer in the loop.

Fixes: 302db0f5b3d8 ("tracing/probes: Add a function to search a member of a struct/union")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
 kernel/trace/trace_btf.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Masami Hiramatsu (Google) Feb. 17, 2024, 12:27 p.m. UTC | #1 
Let me pick this patch because this is a real bugfix.

On Wed, 14 Feb 2024 22:22:23 +0900
"Masami Hiramatsu (Google)" <mhiramat@kernel.org> wrote:

> From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> 
> Fix to search a field from the structure which has anonymous union
> correctly.
> Since the reference `type` pointer was updated in the loop, the search
> loop suddenly aborted where it hits an anonymous union. Thus it can not
> find the field after the anonymous union. This avoids updating the
> cursor `type` pointer in the loop.
> 
> Fixes: 302db0f5b3d8 ("tracing/probes: Add a function to search a member of a struct/union")
> Cc: stable@vger.kernel.org
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> ---
>  kernel/trace/trace_btf.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/trace/trace_btf.c b/kernel/trace/trace_btf.c
> index ca224d53bfdc..5bbdbcbbde3c 100644
> --- a/kernel/trace/trace_btf.c
> +++ b/kernel/trace/trace_btf.c
> @@ -91,8 +91,8 @@ const struct btf_member *btf_find_struct_member(struct btf *btf,
>  	for_each_member(i, type, member) {
>  		if (!member->name_off) {
>  			/* Anonymous union/struct: push it for later use */
> -			type = btf_type_skip_modifiers(btf, member->type, &tid);
> -			if (type && top < BTF_ANON_STACK_MAX) {
> +			if (btf_type_skip_modifiers(btf, member->type, &tid) &&
> +			    top < BTF_ANON_STACK_MAX) {
>  				anon_stack[top].tid = tid;
>  				anon_stack[top++].offset =
>  					cur_offset + member->offset;
>
diff mbox series

Patch

diff --git a/kernel/trace/trace_btf.c b/kernel/trace/trace_btf.c
index ca224d53bfdc..5bbdbcbbde3c 100644
--- a/kernel/trace/trace_btf.c
+++ b/kernel/trace/trace_btf.c
@@ -91,8 +91,8 @@  const struct btf_member *btf_find_struct_member(struct btf *btf,
 	for_each_member(i, type, member) {
 		if (!member->name_off) {
 			/* Anonymous union/struct: push it for later use */
-			type = btf_type_skip_modifiers(btf, member->type, &tid);
-			if (type && top < BTF_ANON_STACK_MAX) {
+			if (btf_type_skip_modifiers(btf, member->type, &tid) &&
+			    top < BTF_ANON_STACK_MAX) {
 				anon_stack[top].tid = tid;
 				anon_stack[top++].offset =
 					cur_offset + member->offset;