[PATCH v0 08/15] bfd: parse build attributes v2's section in input object files
Matthieu Longo
matthieu.longo@arm.com
Mon Mar 10 17:51:21 GMT 2025
---
bfd/elf-attrs.c | 214 +++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 212 insertions(+), 2 deletions(-)
diff --git a/bfd/elf-attrs.c b/bfd/elf-attrs.c
index ab3c80573e5..bd8ae56678a 100644
--- a/bfd/elf-attrs.c
+++ b/bfd/elf-attrs.c
@@ -774,7 +774,214 @@ bfd_elf_parse_attr_section_v1 (bfd *abfd,
}
}
-/* Parse an object attributes section. */
+/* An helper struct for parsing returning the parsed object, the number of bytes
+ read, and whether or not an error occurred. */
+typedef struct {
+ /* Was an error met during parsing. */
+ bool err;
+ /* How many bytes were read ? (until error if an error occurred) */
+ uint64_t read;
+ /* The parsed object. */
+ void *object;
+} BufferReadOp_t ;
+
+#define READ_ULEB128(abfd, var, cursor, end, op) \
+ do \
+ { \
+ bfd_byte *_begin = cursor; \
+ (var) = _bfd_safe_read_leb128 (abfd, &cursor, false, end);\
+ op.read += cursor - _begin; \
+ } \
+ while (0)
+
+#define READ_NTBS(abfd, var, cursor, end, op) \
+ do \
+ { \
+ (var) = strdup ((const char*) cursor); \
+ size_t read_ = strnlen (var, end - cursor) + 1; \
+ op.read += read_; \
+ (cursor) += read_; \
+ } \
+ while (0)
+
+#define READ_UINT8(abfd, var, cursor, end, op) \
+ do \
+ { \
+ (var) = bfd_get_8 (abfd, (cursor)); \
+ (cursor) += sizeof(uint8_t); \
+ op.read += sizeof(uint8_t); \
+ } \
+ while (0)
+
+/* Parse an objet attribute (v2 only). */
+static BufferReadOp_t
+bfd_elf_parse_attr_v2 (bfd *abfd,
+ bfd_byte *cursor,
+ bfd_byte *const end,
+ obj_attr_encoding_v2 attr_type)
+{
+ BufferReadOp_t op = { .err = false, .read = 0, .object = NULL };
+
+ uint32_t attr_tag;
+ READ_ULEB128 (abfd, attr_tag, cursor, end, op);
+
+ union obj_attr_value_v2 vals;
+ switch (attr_type)
+ {
+ case NTBS:
+ READ_NTBS (abfd, vals.string_val, cursor, end, op);
+ break;
+ case ULEB128:
+ READ_ULEB128 (abfd, vals.uint_val, cursor, end, op);
+ break;
+ }
+
+ op.object = _bfd_elf_obj_attr_v2_init (attr_tag, vals);
+ return op;
+}
+
+/* Parse a subsection (object attributes v2 only). */
+static BufferReadOp_t
+bfd_elf_parse_attrs_subsection_v2 (bfd *abfd,
+ bfd_byte *cursor,
+ const uint64_t max_read)
+{
+ BufferReadOp_t op = { .err = false, .read = 0, .object = NULL };
+
+ const uint32_t F_SUBSECTION_LEN = sizeof(uint32_t);
+ /* The minimum subsection length is 5: 4 bytes for the length itself, and 1
+ byte for an empty NUL-terminated string, and no vendor-data. */
+ const uint32_t F_MIN_SUBSECTION_DATA_LEN = F_SUBSECTION_LEN + 1;
+
+ if (max_read <= F_SUBSECTION_LEN)
+ {
+ _bfd_error_handler (_("%pB: error: attributes subsection ends "
+ "prematurely"), abfd);
+ bfd_set_error (bfd_error_malformed_archive);
+ return op;
+ }
+
+ uint32_t subsection_len = bfd_get_32 (abfd, cursor);
+ op.read += F_SUBSECTION_LEN;
+ cursor += F_SUBSECTION_LEN;
+ if (subsection_len > max_read)
+ {
+ _bfd_error_handler (_("%pB: error: bad subsection length (%u > max=%lu)"),
+ abfd, subsection_len, max_read);
+ bfd_set_error (bfd_error_malformed_archive);
+ op.err = true;
+ return op;
+ }
+ /* PR 17531: file: 001-101425-0.004 */
+ else if (subsection_len < F_MIN_SUBSECTION_DATA_LEN)
+ {
+ _bfd_error_handler (_("%pB: error: subsection length of %u is too small"),
+ abfd, subsection_len);
+ bfd_set_error (bfd_error_malformed_archive);
+ op.err = true;
+ return op;
+ }
+
+ size_t subsection_name_len = strnlen ((char *) cursor, subsection_len) + 1;
+ if (subsection_name_len >= subsection_len)
+ {
+ _bfd_error_handler (_("%pB: error: subsection name seems corrupted "
+ "(missing '\\0')"), abfd);
+ bfd_set_error (bfd_error_malformed_archive);
+ op.err = true;
+ return op;
+ }
+ /* Note: if the length of the subsection name is 0 (i.e. the string is '\0'),
+ it is still considered a valid name, even if it is not particularly
+ usefull. */
+
+ unsigned char * const end = cursor + subsection_len - F_SUBSECTION_LEN;
+ BFD_ASSERT (cursor < end);
+
+ const char* subsection_name;
+ READ_NTBS (abfd, subsection_name, cursor, end, op);
+
+ uint8_t optional_raw;
+ READ_UINT8 (abfd, optional_raw, cursor, end, op);
+
+ if (optional_raw > 1)
+ {
+ _bfd_error_handler (_("%pB: error: optional value seems corrupted, got"
+ " %u but only 0x0 (false) or 0x1 (true) are "
+ "valid values."), abfd, optional_raw);
+ bfd_set_error (bfd_error_malformed_archive);
+ op.err = true;
+ free ((void*) subsection_name);
+ return op;
+ }
+
+ uint8_t attr_type_raw;
+ READ_UINT8 (abfd, attr_type_raw, cursor, end, op);
+ if (attr_type_raw > NTBS)
+ {
+ _bfd_error_handler (_("%pB: error: attribute type seems corrupted, got"
+ " %u but only 0x0 (ULEB128) or 0x1 (NTBS) are "
+ "valid types."), abfd, attr_type_raw);
+ bfd_set_error (bfd_error_malformed_archive);
+ op.err = true;
+ free ((void*) subsection_name);
+ return op;
+ }
+
+ const char *vendor_name = get_elf_backend_data (abfd)->obj_attrs_vendor;
+ obj_attr_subsection_scope_v2 scope =
+ (strncmp (subsection_name, vendor_name, strlen (vendor_name)) == 0)
+ ? SUBSEC_PUBLIC
+ : SUBSEC_PRIVATE;
+
+ obj_attr_subsection_v2 *subsec =
+ _bfd_elf_obj_attr_subsection_v2_init (subsection_name, scope, optional_raw,
+ attr_type_raw);
+ while (cursor < end)
+ {
+ BufferReadOp_t op_ =
+ bfd_elf_parse_attr_v2 (abfd, cursor, end, attr_type_raw);
+ LINKED_LIST_APPEND(obj_attr_v2) (subsec, op_.object);
+ op.read += op_.read;
+ cursor += op_.read;
+ }
+
+ op.object = subsec;
+
+ BFD_ASSERT (cursor == end);
+
+ return op;
+}
+
+/* Parse the list of subsections (object attributes v2 only). */
+static void
+bfd_elf_parse_attr_section_v2 (bfd *abfd,
+ Elf_Internal_Shdr * hdr,
+ bfd_byte *cursor)
+{
+ obj_attr_subsection_list *subsecs = &elf_obj_attr_subsections (abfd);
+ BufferReadOp_t op;
+ for (uint64_t remaining = hdr->sh_size - 1; // already read 'A'
+ remaining > 0;
+ remaining -= op.read, cursor += op.read)
+ {
+ op = bfd_elf_parse_attrs_subsection_v2 (abfd, cursor, remaining);
+ if (op.err)
+ {
+ _bfd_error_handler (_("%pB: error: could not parse subsection at "
+ "offset %lx"),
+ abfd, hdr->sh_size - remaining);
+ bfd_set_error (bfd_error_wrong_format);
+ break;
+ }
+ else
+ LINKED_LIST_APPEND(obj_attr_subsection_v2) (subsecs,
+ (obj_attr_subsection_v2 *) op.object);
+ }
+}
+
+/* Parse an object attributes section.
+ Note: The parsing setup is common between object attributes v1 and v2. */
void
_bfd_elf_parse_attributes (bfd *abfd, Elf_Internal_Shdr * hdr)
{
@@ -812,7 +1019,10 @@ _bfd_elf_parse_attributes (bfd *abfd, Elf_Internal_Shdr * hdr)
++cursor;
- bfd_elf_parse_attr_section_v1 (abfd, hdr, cursor);
+ if (get_elf_backend_data (abfd)->obj_attrs_version == 2)
+ bfd_elf_parse_attr_section_v2 (abfd, hdr, cursor);
+ else
+ bfd_elf_parse_attr_section_v1 (abfd, hdr, cursor);
free_data:
free (data);
--
2.48.1
More information about the Binutils
mailing list