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PR22209, invalid memory read in find_abstract_instance_name
- From: Alan Modra <amodra at gmail dot com>
- To: binutils at sourceware dot org
- Date: Tue, 26 Sep 2017 22:18:03 +0930
- Subject: PR22209, invalid memory read in find_abstract_instance_name
- Authentication-results: sourceware.org; auth=none
This patch adds bounds checking for DW_FORM_ref_addr die refs, and
calculates them relative to the first .debug_info section. See the
big comment for why calculating relative to the current .debug_info
section was wrong for relocatable object files.
PR 22209
* dwarf2.c (struct comp_unit): Delete sec_info_ptr field.
(find_abstract_instance_name): Calculate DW_FORM_ref_addr relative
to stash->info_ptr_memory, and check die_ref is within that memory.
Set info_ptr_end correctly when another CU is refd. Check die_ref
for DW_FORM_ref4 etc. is within CU.
diff --git a/bfd/dwarf2.c b/bfd/dwarf2.c
index 225b4a9..ad06120 100644
--- a/bfd/dwarf2.c
+++ b/bfd/dwarf2.c
@@ -125,8 +125,7 @@ struct dwarf2_debug
/* A pointer to the memory block allocated for info_ptr. Neither
info_ptr nor sec_info_ptr are guaranteed to stay pointing to the
- beginning of the malloc block. This is used only to free the
- memory later. */
+ beginning of the malloc block. */
bfd_byte *info_ptr_memory;
/* Pointer to the symbol table. */
@@ -250,9 +249,6 @@ struct comp_unit
by its reference. */
bfd_byte *info_ptr_unit;
- /* Pointer to the start of the debug section, for DW_FORM_ref_addr. */
- bfd_byte *sec_info_ptr;
-
/* The offset into .debug_line of the line number table. */
unsigned long line_offset;
@@ -2849,21 +2845,37 @@ find_abstract_instance_name (struct comp_unit *unit,
if (attr_ptr->form == DW_FORM_ref_addr)
{
/* We only support DW_FORM_ref_addr within the same file, so
- any relocations should be resolved already. */
- if (!die_ref)
+ any relocations should be resolved already. Check this by
+ testing for a zero die_ref; There can't be a valid reference
+ to the header of a .debug_info section.
+ DW_FORM_ref_addr is an offset relative to .debug_info.
+ Normally when using the GNU linker this is accomplished by
+ emitting a symbolic reference to a label, because .debug_info
+ sections are linked at zero. When there are multiple section
+ groups containing .debug_info, as there might be in a
+ relocatable object file, it would be reasonable to assume that
+ a symbolic reference to a label in any .debug_info section
+ might be used. Since we lay out multiple .debug_info
+ sections at non-zero VMAs (see place_sections), and read
+ them contiguously into stash->info_ptr_memory, that means
+ the reference is relative to stash->info_ptr_memory. */
+ size_t total;
+
+ info_ptr = unit->stash->info_ptr_memory;
+ info_ptr_end = unit->stash->info_ptr_end;
+ total = info_ptr_end - info_ptr;
+ if (!die_ref || die_ref >= total)
{
_bfd_error_handler
- (_("Dwarf Error: Abstract instance DIE ref zero."));
+ (_("Dwarf Error: Invalid abstract instance DIE ref."));
bfd_set_error (bfd_error_bad_value);
return FALSE;
}
-
- info_ptr = unit->sec_info_ptr + die_ref;
- info_ptr_end = unit->end_ptr;
+ info_ptr += die_ref;
/* Now find the CU containing this pointer. */
if (info_ptr >= unit->info_ptr_unit && info_ptr < unit->end_ptr)
- ;
+ info_ptr_end = unit->end_ptr;
else
{
/* Check other CUs to see if they contain the abbrev. */
@@ -2879,7 +2891,10 @@ find_abstract_instance_name (struct comp_unit *unit,
break;
if (u)
- unit = u;
+ {
+ unit = u;
+ info_ptr_end = unit->end_ptr;
+ }
/* else FIXME: What do we do now ? */
}
}
@@ -2902,8 +2917,22 @@ find_abstract_instance_name (struct comp_unit *unit,
}
else
{
- info_ptr = unit->info_ptr_unit + die_ref;
+ /* DW_FORM_ref1, DW_FORM_ref2, DW_FORM_ref4, DW_FORM_ref8 or
+ DW_FORM_ref_udata. These are all references relative to the
+ start of the current CU. */
+ size_t total;
+
+ info_ptr = unit->info_ptr_unit;
info_ptr_end = unit->end_ptr;
+ total = info_ptr_end - info_ptr;
+ if (!die_ref || die_ref >= total)
+ {
+ _bfd_error_handler
+ (_("Dwarf Error: Invalid abstract instance DIE ref."));
+ bfd_set_error (bfd_error_bad_value);
+ return FALSE;
+ }
+ info_ptr += die_ref;
}
abbrev_number = _bfd_safe_read_leb128 (abfd, info_ptr, &bytes_read,
@@ -3451,7 +3480,6 @@ parse_comp_unit (struct dwarf2_debug *stash,
unit->end_ptr = end_ptr;
unit->stash = stash;
unit->info_ptr_unit = info_ptr_unit;
- unit->sec_info_ptr = stash->sec_info_ptr;
for (i = 0; i < abbrev->num_attrs; ++i)
{
--
Alan Modra
Australia Development Lab, IBM