On 4/28/23 8:50 AM, Ilya Leoshkevich wrote:
btf_dump test fails on s390x with the following error:
unexpected return value dumping fs_context: actual -7 != expected 280
This happens when processing the fs_context.phase member: its type size
is 4, but there are less bytes left until the end of the struct. The
problem is that btf_dump_type_data_check_overflow() does not handle
bitfields.
Add bitfield support; make sure that byte boundaries, which are
computed from bit boundaries, are rounded up.
Ilya, Martin has submitted a patch yesterday to fix the issue:
https://lore.kernel.org/bpf/20230428013638.1581263-1-martin.lau@xxxxxxxxx/
Fixes: 920d16af9b42 ("libbpf: BTF dumper support for typed data")
Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
---
tools/lib/bpf/btf_dump.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index 580985ee5545..f8b538e8d753 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -2250,9 +2250,11 @@ static int btf_dump_type_data_check_overflow(struct btf_dump *d,
const struct btf_type *t,
__u32 id,
const void *data,
- __u8 bits_offset)
+ __u8 bits_offset,
+ __u8 bit_sz)
{
__s64 size = btf__resolve_size(d->btf, id);
+ const void *end;
if (size < 0 || size >= INT_MAX) {
pr_warn("unexpected size [%zu] for id [%u]\n",
@@ -2280,7 +2282,11 @@ static int btf_dump_type_data_check_overflow(struct btf_dump *d,
case BTF_KIND_PTR:
case BTF_KIND_ENUM:
case BTF_KIND_ENUM64:
- if (data + bits_offset / 8 + size > d->typed_dump->data_end)
+ if (bit_sz)
+ end = data + (bits_offset + bit_sz + 7) / 8;
+ else
+ end = data + (bits_offset + 7) / 8 + size;
+ if (end > d->typed_dump->data_end)
return -E2BIG;
break;
default:
@@ -2407,7 +2413,7 @@ static int btf_dump_dump_type_data(struct btf_dump *d,
{
int size, err = 0;
- size = btf_dump_type_data_check_overflow(d, t, id, data, bits_offset);
+ size = btf_dump_type_data_check_overflow(d, t, id, data, bits_offset, bit_sz);
if (size < 0)
return size;
err = btf_dump_type_data_check_zero(d, t, id, data, bits_offset, bit_sz);
