On 9/9/22 2:21 AM, Lorenz Bauer wrote:
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: eb3f595dab40 ("bpf: btf: Validate type reference")
The fix tag should be
Fixes: a0791f0df7d2 ("bpf: fix BTF limits")
Signed-off-by: Lorenz Bauer <oss@xxxxxx>
---
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 7e64447659f3..36fd4b509294 100644
--- 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;
The change makes sense.
The kernel's vmlinux and module btf parsing doesn't go through this
resolve check though. Are you trying to __sys_bpf(BPF_BTF_LOAD) the btf
from the vmlinux file into the kernel ?
