Merge branch 'fix-BTF-enum'
Yoshiki Komachi says:
====================
btf_enum_check_member() checked if the size of "enum" as a struct
member exceeded struct_size or not. Then, the function compared it
with the size of "int". Although the size of "enum" is 4-byte by
default (i.e., equivalent to "int"), the packing feature enables
us to reduce it, as illustrated by the following example:
struct A {
char m;
enum { E0, E1 } __attribute__((packed)) n;
};
With such a setup above, the bpf loader gave an error attempting
to load it:
------------------------------------------------------------------
...
[3] ENUM (anon) size=1 vlen=2
E0 val=0
E1 val=1
[4] STRUCT A size=2 vlen=2
m type_id=2 bits_offset=0
n type_id=3 bits_offset=8
[4] STRUCT A size=2 vlen=2
n type_id=3 bits_offset=8 Member exceeds struct_size
libbpf: Error loading .BTF into kernel: -22.
------------------------------------------------------------------
The related issue was previously fixed by the commit 9eea98497951 ("bpf:
fix BTF verification of enums"). On the other hand, this series fixes
this issue as well, and adds a selftest program for it.
Changes in v2:
- change an example in commit message based on Andrii's review
- add a selftest program for packed "enum" type members in struct/union
====================
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 7871400..32ab922 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -2418,7 +2418,7 @@
struct_size = struct_type->size;
bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
- if (struct_size - bytes_offset < sizeof(int)) {
+ if (struct_size - bytes_offset < member_type->size) {
btf_verifier_log_member(env, struct_type, member,
"Member exceeds struct_size");
return -EINVAL;
diff --git a/tools/testing/selftests/bpf/test_btf.c b/tools/testing/selftests/bpf/test_btf.c
index 93040ca..8da77cd 100644
--- a/tools/testing/selftests/bpf/test_btf.c
+++ b/tools/testing/selftests/bpf/test_btf.c
@@ -1062,6 +1062,48 @@
.err_str = "Member exceeds struct_size",
},
+/* Test member unexceeds the size of struct
+ *
+ * enum E {
+ * E0,
+ * E1,
+ * };
+ *
+ * struct A {
+ * char m;
+ * enum E __attribute__((packed)) n;
+ * };
+ */
+{
+ .descr = "size check test #5",
+ .raw_types = {
+ /* int */ /* [1] */
+ BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, sizeof(int)),
+ /* char */ /* [2] */
+ BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 8, 1),
+ /* enum E { */ /* [3] */
+ BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_ENUM, 0, 2), 1),
+ BTF_ENUM_ENC(NAME_TBD, 0),
+ BTF_ENUM_ENC(NAME_TBD, 1),
+ /* } */
+ /* struct A { */ /* [4] */
+ BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 2),
+ BTF_MEMBER_ENC(NAME_TBD, 2, 0), /* char m; */
+ BTF_MEMBER_ENC(NAME_TBD, 3, 8),/* enum E __attribute__((packed)) n; */
+ /* } */
+ BTF_END_RAW,
+ },
+ .str_sec = "\0E\0E0\0E1\0A\0m\0n",
+ .str_sec_size = sizeof("\0E\0E0\0E1\0A\0m\0n"),
+ .map_type = BPF_MAP_TYPE_ARRAY,
+ .map_name = "size_check5_map",
+ .key_size = sizeof(int),
+ .value_size = 2,
+ .key_type_id = 1,
+ .value_type_id = 4,
+ .max_entries = 4,
+},
+
/* typedef const void * const_void_ptr;
* struct A {
* const_void_ptr m;
