On 18/06/2023 14:08, Jiri Olsa wrote:
> On Fri, Jun 16, 2023 at 06:17:22PM +0100, Alan Maguire wrote:
>
> SNIP
>
>> static int btf_sec_info_cmp(const void *a, const void *b)
>> @@ -5193,32 +5246,37 @@ static int btf_check_sec_info(struct btf_verifier_env *env,
>> u32 btf_data_size)
>> {
>> struct btf_sec_info secs[ARRAY_SIZE(btf_sec_info_offset)];
>> - u32 total, expected_total, i;
>> + u32 nr_secs = ARRAY_SIZE(btf_sec_info_offset);
>> + u32 total, expected_total, gap, i;
>> const struct btf_header *hdr;
>> const struct btf *btf;
>>
>> btf = env->btf;
>> hdr = &btf->hdr;
>>
>> + if (hdr->hdr_len < sizeof(struct btf_header))
>> + nr_secs--;
>> +
>> /* Populate the secs from hdr */
>> - for (i = 0; i < ARRAY_SIZE(btf_sec_info_offset); i++)
>> + for (i = 0; i < nr_secs; i++)
>> secs[i] = *(struct btf_sec_info *)((void *)hdr +
>> btf_sec_info_offset[i]);
>>
>> - sort(secs, ARRAY_SIZE(btf_sec_info_offset),
>> + sort(secs, nr_secs,
>> sizeof(struct btf_sec_info), btf_sec_info_cmp, NULL);
>>
>> /* Check for gaps and overlap among sections */
>> total = 0;
>> expected_total = btf_data_size - hdr->hdr_len;
>> - for (i = 0; i < ARRAY_SIZE(btf_sec_info_offset); i++) {
>> + for (i = 0; i < nr_secs; i++) {
>> if (expected_total < secs[i].off) {
>> btf_verifier_log(env, "Invalid section offset");
>> return -EINVAL;
>> }
>> - if (total < secs[i].off) {
>> - /* gap */
>> - btf_verifier_log(env, "Unsupported section found");
>> + gap = secs[i].off - total;
>> + if (gap >= 4) {
>> + /* gap larger than alignment gap */
>> + btf_verifier_log(env, "Unsupported section gap found");
>> return -EINVAL;
>
> this sems to break several btf header tests with:
>
> do_test_raw:PASS:check 0 nsec
> do_test_raw:FAIL:check expected err_str:Unsupported section found
>
> magic: 0xeb9f
> version: 1
> flags: 0x0
> hdr_len: 40
> type_off: 4
> type_len: 16
> str_off: 16
> str_len: 5
> btf_total_size: 61
> Unsupported section gap found
> #23/48 btf/btf_header test. Gap between hdr and type:FAIL
>
>
thanks for spotting this Jiri! I've reworked the logic and the
messages for v3 (in progress), and these pass now.
Alan
> jirka
>
>> }
>> if (total > secs[i].off) {
>> @@ -5230,7 +5288,7 @@ static int btf_check_sec_info(struct btf_verifier_env *env,
>> "Total section length too long");
>> return -EINVAL;
>> }
>> - total += secs[i].len;
>> + total += secs[i].len + gap;
>> }
>>
>> /* There is data other than hdr and known sections */
>> @@ -5293,7 +5351,7 @@ static int btf_parse_hdr(struct btf_verifier_env *env)
>> return -ENOTSUPP;
>> }
>>
>> - if (hdr->flags) {
>> + if (hdr->flags & ~(BTF_FLAG_CRC_SET | BTF_FLAG_BASE_CRC_SET)) {
>> btf_verifier_log(env, "Unsupported flags");
>> return -ENOTSUPP;
>> }
>> @@ -5530,6 +5588,10 @@ static struct btf *btf_parse(const union bpf_attr *attr, bpfptr_t uattr, u32 uat
>> if (err)
>> goto errout;
>>
>> + err = btf_parse_kind_layout_sec(env);
>> + if (err)
>> + goto errout;
>> +
>> err = btf_parse_type_sec(env);
>> if (err)
>> goto errout;
>> --
>> 2.39.3
>>
