diff options
| -rw-r--r-- | tools/lib/bpf/btf.c | 20 |
1 files changed, 17 insertions, 3 deletions
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 820f7fc8ebcc..1b8d8cdd3575 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -1663,7 +1663,7 @@ static __u32 btf_hash_struct(struct btf_type *t) * IDs. This check is performed during type graph equivalence check and * referenced types equivalence is checked separately. */ -static bool btf_equal_struct(struct btf_type *t1, struct btf_type *t2) +static bool btf_shallow_equal_struct(struct btf_type *t1, struct btf_type *t2) { struct btf_member *m1, *m2; __u16 vlen; @@ -2124,7 +2124,7 @@ static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id, struct btf_member *cand_m, *canon_m; __u16 vlen; - if (!btf_equal_struct(cand_type, canon_type)) + if (!btf_shallow_equal_struct(cand_type, canon_type)) return 0; vlen = BTF_INFO_VLEN(cand_type->info); cand_m = (struct btf_member *)(cand_type + 1); @@ -2265,7 +2265,7 @@ static void btf_dedup_merge_hypot_map(struct btf_dedup *d) static int btf_dedup_struct_type(struct btf_dedup *d, __u32 type_id) { struct btf_dedup_node *cand_node; - struct btf_type *t; + struct btf_type *cand_type, *t; /* if we don't find equivalent type, then we are canonical */ __u32 new_id = type_id; __u16 kind; @@ -2285,6 +2285,20 @@ static int btf_dedup_struct_type(struct btf_dedup *d, __u32 type_id) for_each_dedup_cand(d, h, cand_node) { int eq; + /* + * Even though btf_dedup_is_equiv() checks for + * btf_shallow_equal_struct() internally when checking two + * structs (unions) for equivalence, we need to guard here + * from picking matching FWD type as a dedup candidate. + * This can happen due to hash collision. In such case just + * relying on btf_dedup_is_equiv() would lead to potentially + * creating a loop (FWD -> STRUCT and STRUCT -> FWD), because + * FWD and compatible STRUCT/UNION are considered equivalent. + */ + cand_type = d->btf->types[cand_node->type_id]; + if (!btf_shallow_equal_struct(t, cand_type)) + continue; + btf_dedup_clear_hypot_map(d); eq = btf_dedup_is_equiv(d, type_id, cand_node->type_id); if (eq < 0) |