From e98fdf1ab07243fe467caadd0d033b44b8ca20c7 Mon Sep 17 00:00:00 2001 From: Alan Modra Date: Fri, 6 Oct 2017 14:14:21 +1030 Subject: [PATCH] DWARF header checks This patch tidies DWARF header checks, consolidating the "negative" checks (which are really overflow checks) with the section size check. In a number of cases this also ensures that small negative lengths are caught. For instance hdrptr = start + arange.ar_length + initial_length_size; if (hdrptr < start || hdrptr > end) does not detect ar_length in the range [-initial_length_size,-1]. * dwarf.c (process_debug_info): Consolidate header length checks. (display_debug_pubnames_worker): Use "start" to read header. Properly check header length and report errors earlier. Simplify loop printing pubnames. (get_line_filename_and_dirname): Catch small negative "length" values. (display_debug_aranges): Likewise. Report header errors earlier using standardized message. (display_debug_names): Likewise. --- binutils/ChangeLog | 12 ++++ binutils/dwarf.c | 169 ++++++++++++++++++++++----------------------- 2 files changed, 95 insertions(+), 86 deletions(-) diff --git a/binutils/ChangeLog b/binutils/ChangeLog index 4fb4eb464a1..ca4990ea077 100644 --- a/binutils/ChangeLog +++ b/binutils/ChangeLog @@ -1,3 +1,15 @@ +2017-10-06 Alan Modra + + * dwarf.c (process_debug_info): Consolidate header length checks. + (display_debug_pubnames_worker): Use "start" to read header. + Properly check header length and report errors earlier. + Simplify loop printing pubnames. + (get_line_filename_and_dirname): Catch small negative "length" + values. + (display_debug_aranges): Likewise. Report header errors + earlier using standardized message. + (display_debug_names): Likewise. + 2017-10-05 Joseph Myers * readelf.c (decode_arm_unwind): Initialize res to TRUE. diff --git a/binutils/dwarf.c b/binutils/dwarf.c index f8c726cb30e..91f95ff0682 100644 --- a/binutils/dwarf.c +++ b/binutils/dwarf.c @@ -2590,6 +2590,7 @@ process_debug_info (struct dwarf_section *section, unsigned char *tags; int level, last_level, saved_level; dwarf_vma cu_offset; + unsigned long sec_off; unsigned int offset_size; unsigned int initial_length_size; dwarf_vma signature_high = 0; @@ -2729,20 +2730,13 @@ process_debug_info (struct dwarf_section *section, } } - if (cu_offset + compunit.cu_length + initial_length_size - > section->size) + sec_off = cu_offset + initial_length_size; + if (sec_off + compunit.cu_length < sec_off + || sec_off + compunit.cu_length > section->size) { - warn (_("Debug info is corrupted, length of CU at %s" - " extends beyond end of section (length = %s)\n"), - dwarf_vmatoa ("x", cu_offset), - dwarf_vmatoa ("x", compunit.cu_length)); - num_units = unit; - break; - } - else if (compunit.cu_length + initial_length_size < initial_length_size) - { - warn (_("Debug info is corrupted, length of CU at %s is negative (%s)\n"), - dwarf_vmatoa ("x", cu_offset), + warn (_("Debug info is corrupted, %s header at %#lx has length %s\n"), + section->name, + (unsigned long) cu_offset, dwarf_vmatoa ("x", compunit.cu_length)); num_units = unit; break; @@ -2751,13 +2745,6 @@ process_debug_info (struct dwarf_section *section, tags = hdrptr; start += compunit.cu_length + initial_length_size; - if (start > end) - { - warn (_("Debug info is corrupt. CU at %s extends beyond end of section"), - dwarf_vmatoa ("x", cu_offset)); - start = end; - } - if (compunit.cu_version < 2 || compunit.cu_version > 5) { warn (_("CU at offset %s contains corrupt or " @@ -4489,16 +4476,13 @@ display_debug_pubnames_worker (struct dwarf_section *section, while (start < end) { unsigned char *data; - unsigned char *adr; - dwarf_vma offset; + unsigned long sec_off; unsigned int offset_size, initial_length_size; - data = start; - - SAFE_BYTE_GET_AND_INC (names.pn_length, data, 4, end); + SAFE_BYTE_GET_AND_INC (names.pn_length, start, 4, end); if (names.pn_length == 0xffffffff) { - SAFE_BYTE_GET_AND_INC (names.pn_length, data, 8, end); + SAFE_BYTE_GET_AND_INC (names.pn_length, start, 8, end); offset_size = 8; initial_length_size = 12; } @@ -4508,6 +4492,20 @@ display_debug_pubnames_worker (struct dwarf_section *section, initial_length_size = 4; } + sec_off = start - section->start; + if (sec_off + names.pn_length < sec_off + || sec_off + names.pn_length > section->size) + { + warn (_("Debug info is corrupted, %s header at %#lx has length %s\n"), + section->name, + sec_off - initial_length_size, + dwarf_vmatoa ("x", names.pn_length)); + break; + } + + data = start; + start += names.pn_length; + SAFE_BYTE_GET_AND_INC (names.pn_version, data, 2, end); SAFE_BYTE_GET_AND_INC (names.pn_offset, data, offset_size, end); @@ -4519,18 +4517,6 @@ display_debug_pubnames_worker (struct dwarf_section *section, SAFE_BYTE_GET_AND_INC (names.pn_size, data, offset_size, end); - adr = start + names.pn_length + initial_length_size; - /* PR 17531: file: 7615b6b2. */ - if ((dwarf_signed_vma) names.pn_length < 0 - /* PR 17531: file: a5dbeaa7. */ - || adr < start) - { - warn (_("Negative length for public name: 0x%lx\n"), (long) names.pn_length); - start = end; - } - else - start = adr; - printf (_(" Length: %ld\n"), (long) names.pn_length); printf (_(" Version: %d\n"), @@ -4558,51 +4544,51 @@ display_debug_pubnames_worker (struct dwarf_section *section, else printf (_("\n Offset\tName\n")); - do + while (1) { bfd_size_type maxprint; + dwarf_vma offset; SAFE_BYTE_GET (offset, data, offset_size, end); - if (offset != 0) - { - data += offset_size; - if (data >= end) - break; - maxprint = (end - data) - 1; + if (offset == 0) + break; - if (is_gnu) - { - unsigned int kind_data; - gdb_index_symbol_kind kind; - const char *kind_name; - int is_static; - - SAFE_BYTE_GET (kind_data, data, 1, end); - data++; - maxprint --; - /* GCC computes the kind as the upper byte in the CU index - word, and then right shifts it by the CU index size. - Left shift KIND to where the gdb-index.h accessor macros - can use it. */ - kind_data <<= GDB_INDEX_CU_BITSIZE; - kind = GDB_INDEX_SYMBOL_KIND_VALUE (kind_data); - kind_name = get_gdb_index_symbol_kind_name (kind); - is_static = GDB_INDEX_SYMBOL_STATIC_VALUE (kind_data); - printf (" %-6lx %s,%-10s %.*s\n", - (unsigned long) offset, is_static ? _("s") : _("g"), - kind_name, (int) maxprint, data); - } - else - printf (" %-6lx\t%.*s\n", - (unsigned long) offset, (int) maxprint, data); + data += offset_size; + if (data >= end) + break; + maxprint = (end - data) - 1; - data += strnlen ((char *) data, maxprint) + 1; - if (data >= end) - break; + if (is_gnu) + { + unsigned int kind_data; + gdb_index_symbol_kind kind; + const char *kind_name; + int is_static; + + SAFE_BYTE_GET (kind_data, data, 1, end); + data++; + maxprint --; + /* GCC computes the kind as the upper byte in the CU index + word, and then right shifts it by the CU index size. + Left shift KIND to where the gdb-index.h accessor macros + can use it. */ + kind_data <<= GDB_INDEX_CU_BITSIZE; + kind = GDB_INDEX_SYMBOL_KIND_VALUE (kind_data); + kind_name = get_gdb_index_symbol_kind_name (kind); + is_static = GDB_INDEX_SYMBOL_STATIC_VALUE (kind_data); + printf (" %-6lx %s,%-10s %.*s\n", + (unsigned long) offset, is_static ? _("s") : _("g"), + kind_name, (int) maxprint, data); } + else + printf (" %-6lx\t%.*s\n", + (unsigned long) offset, (int) maxprint, data); + + data += strnlen ((char *) data, maxprint) + 1; + if (data >= end) + break; } - while (offset != 0); } printf ("\n"); @@ -4735,7 +4721,8 @@ get_line_filename_and_dirname (dwarf_vma line_offset, offset_size = 4; initial_length_size = 4; } - if (length + initial_length_size > section->size) + if (length + initial_length_size < length + || length + initial_length_size > section->size) return NULL; SAFE_BYTE_GET_AND_INC (version, hdrptr, 2, end); @@ -6027,6 +6014,7 @@ display_debug_aranges (struct dwarf_section *section, unsigned char *addr_ranges; dwarf_vma length; dwarf_vma address; + unsigned long sec_off; unsigned char address_size; int excess; unsigned int offset_size; @@ -6047,6 +6035,17 @@ display_debug_aranges (struct dwarf_section *section, initial_length_size = 4; } + sec_off = hdrptr - section->start; + if (sec_off + arange.ar_length < sec_off + || sec_off + arange.ar_length > section->size) + { + warn (_("Debug info is corrupted, %s header at %#lx has length %s\n"), + section->name, + sec_off - initial_length_size, + dwarf_vmatoa ("x", arange.ar_length)); + break; + } + SAFE_BYTE_GET_AND_INC (arange.ar_version, hdrptr, 2, end); SAFE_BYTE_GET_AND_INC (arange.ar_info_offset, hdrptr, offset_size, end); @@ -6109,13 +6108,7 @@ display_debug_aranges (struct dwarf_section *section, if (excess) addr_ranges += (2 * address_size) - excess; - hdrptr = start + arange.ar_length + initial_length_size; - if (hdrptr < start || hdrptr > end) - { - error (_("Excessive header length: %lx\n"), (long) arange.ar_length); - break; - } - start = hdrptr; + start += arange.ar_length + initial_length_size; while (addr_ranges + 2 * address_size <= start) { @@ -8030,6 +8023,7 @@ display_debug_names (struct dwarf_section *section, void *file) uint32_t bucket_count, name_count, abbrev_table_size; uint32_t augmentation_string_size; unsigned int i; + unsigned long sec_off; unit_start = hdrptr; @@ -8046,11 +8040,14 @@ display_debug_names (struct dwarf_section *section, void *file) offset_size = 4; unit_end = hdrptr + unit_length; - if ((hdrptr - section->start) + unit_length > section->size) + sec_off = hdrptr - section->start; + if (sec_off + unit_length < sec_off + || sec_off + unit_length > section->size) { - warn (_("The length field (0x%lx) for unit 0x%lx in the debug_names " - "header is wrong - the section is too small\n"), - (long) unit_length, (long) (unit_start - section->start)); + warn (_("Debug info is corrupted, %s header at %#lx has length %s\n"), + section->name, + (unsigned long) (unit_start - section->start), + dwarf_vmatoa ("x", unit_length)); return 0; } -- 2.30.2