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tracing/probes: Fix anon_stack check for unnamed bitfields in btf_find_struct_member

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btf_find_struct_member() traverses into nested anonymous structures
and unions by pushing members with !member->name_off onto anon_stack.
However, it does not consider the unnamed bitfields (e.g. `int : 5`
or `unsigned int : 0`) which also have member->name_off == 0.

If such an unnamed bitfield is pushed to anon_stack, the
btf_find_struct_member() return an error even if there are other
valid entries in anon_stack.

To fix this, only push unnamed struct/union members to anon_stack.
Also move the btf_type_is_struct() check to the entry of this function
because now it is sure only struct/union are pushed to anon_stack.

Link: https://lore.kernel.org/all/178827249775.123716.7813217688423513612.stgit@devnote2/

Fixes: 302db0f5b3 ("tracing/probes: Add a function to search a member of a struct/union")
Cc: stable@vger.kernel.org
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://lore.kernel.org/all/20260830143859.D56991F00A3D@smtp.kernel.org/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Masami Hiramatsu (Google)
2026-09-01 23:21:37 +09:00
parent 738ef4cd82
commit f36d94a20c
1 changed files with 6 additions and 6 deletions
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12
kernel/trace/trace_btf.c
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@@ -74,24 +74,24 @@ const struct btf_member *btf_find_struct_member(struct btf *btf,
{
struct btf_anon_stack *anon_stack;
const struct btf_member *member;
const struct btf_type *mtype;
u32 tid, cur_offset = 0;
const char *name;
int i, top = 0;
if (!btf_type_is_struct(type))
return ERR_PTR(-EINVAL);
anon_stack = kzalloc_objs(*anon_stack, BTF_ANON_STACK_MAX);
if (!anon_stack)
return ERR_PTR(-ENOMEM);
retry:
if (!btf_type_is_struct(type)) {
member = ERR_PTR(-EINVAL);
goto out;
}
for_each_member(i, type, member) {
if (!member->name_off) {
/* Anonymous union/struct: push it for later use */
if (btf_type_skip_modifiers(btf, member->type, &tid) &&
mtype = btf_type_skip_modifiers(btf, member->type, &tid);
if (mtype && btf_type_is_struct(mtype) &&
top < BTF_ANON_STACK_MAX) {
anon_stack[top].tid = tid;
anon_stack[top++].offset =