Fix the way modifiers are skipped while walking pointers. Otherwise second
level dereferences of 'const struct foo *' will be rejected by the verifier.
Fixes: 9e15db66136a ("bpf: Implement accurate raw_tp context access via BTF")
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
---
kernel/bpf/btf.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index b7c1660fb594..a289f2915ba8 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3931,6 +3931,7 @@ int btf_struct_access(struct bpf_verifier_log *log,
if (btf_type_is_ptr(mtype)) {
const struct btf_type *stype;
+ u32 id;
if (msize != size || off != moff) {
bpf_log(log,
@@ -3939,12 +3940,9 @@ int btf_struct_access(struct bpf_verifier_log *log,
return -EACCES;
}
- stype = btf_type_by_id(btf_vmlinux, mtype->type);
- /* skip modifiers */
- while (btf_type_is_modifier(stype))
- stype = btf_type_by_id(btf_vmlinux, stype->type);
+ stype = btf_type_skip_modifiers(btf_vmlinux, mtype->type, &id);
if (btf_type_is_struct(stype)) {
- *next_btf_id = mtype->type;
+ *next_btf_id = id;
return PTR_TO_BTF_ID;
}
}
--
2.23.0
