bpf: btf: fix truncated last_member_type_id in btf_struct_resolve

When trying to finish resolving a struct member, btf_struct_resolve
saves the member type id in a u16 temporary variable. This truncates
the 32 bit type id value if it exceeds UINT16_MAX.

As a result, structs that have members with type ids > UINT16_MAX and
which need resolution will fail with a message like this:

    [67414] STRUCT ff_device size=120 vlen=12
        effect_owners type_id=67434 bits_offset=960 Member exceeds struct_size

Fix this by changing the type of last_member_type_id to u32.

Fixes: a0791f0df7d2 ("bpf: fix BTF limits")
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Lorenz Bauer <oss@lmb.io>
Link: https://lore.kernel.org/r/20220910110120.339242-1-oss@lmb.io
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 7e64447659f3db7f6b8c76905cc1a2fe34921e08..36fd4b509294abb4d9f22da556dae3ebaac1bd62 100644 (file)
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3128,7 +3128,7 @@ static int btf_struct_resolve(struct btf_verifier_env *env,
        if (v->next_member) {
                const struct btf_type *last_member_type;
                const struct btf_member *last_member;
-               u16 last_member_type_id;
+               u32 last_member_type_id;
 
                last_member = btf_type_member(v->t) + v->next_member - 1;
                last_member_type_id = last_member->type;