[PATCH 5.19 234/717] bpf: btf: fix truncated last_member_type_id in btf_struct_resolve

Greg Kroah-Hartman
2022-10-22T07:57:46Z

From: Lorenz Bauer <oss@lmb.io>

[ Upstream commit a37a32583e282d8d815e22add29bc1e91e19951a ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/bpf/btf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index eb12d4f705cc..ff4a2c0b14ea 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3120,7 +3120,7 @@ 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;
--
2.35.1