PR29370, infinite loop in display_debug_abbrev

PR29370, infinite loop in display_debug_abbrev

[Alan Modra]

The PR29370 testcase is a fuzzed object file with multiple
.trace_abbrev sections.  Multiple .trace_abbrev or .debug_abbrev
sections are not a violation of the DWARF standard.  The DWARF5
standard even gives an example of multiple .debug_abbrev sections
contained in groups.  Caching and lookup of processed abbrevs thus
needs to be done by section and offset rather than base and offset.
(Why base anyway?)  Or, since section contents are kept, by a pointer
into the contents.

	PR 29370
	* dwarf.c (struct abbrev_list): Replace abbrev_base and
	abbrev_offset with raw field.
	(find_abbrev_list_by_abbrev_offset): Delete.
	(find_abbrev_list_by_raw_abbrev): New function.
	(process_abbrev_set): Set list->raw and list->next.
	(find_and_process_abbrev_set): Replace abbrev list lookup with
	new function.  Don't set list abbrev_base, abbrev_offset or next.

diff --git a/binutils/dwarf.c b/binutils/dwarf.c
index 2fc352f74c5..99fb3566994 100644
--- a/binutils/dwarf.c
+++ b/binutils/dwarf.c
@@ -856,8 +856,7 @@ typedef struct abbrev_list
 {
   abbrev_entry *        first_abbrev;
   abbrev_entry *        last_abbrev;
-  dwarf_vma             abbrev_base;
-  dwarf_vma             abbrev_offset;
+  unsigned char *       raw;
   struct abbrev_list *  next;
   unsigned char *       start_of_next_abbrevs;
 }
@@ -946,14 +945,12 @@ free_all_abbrevs (void)
 }
 
 static abbrev_list *
-find_abbrev_list_by_abbrev_offset (dwarf_vma abbrev_base,
-				   dwarf_vma abbrev_offset)
+find_abbrev_list_by_raw_abbrev (unsigned char *raw)
 {
   abbrev_list * list;
 
   for (list = abbrev_lists; list != NULL; list = list->next)
-    if (list->abbrev_base == abbrev_base
-	&& list->abbrev_offset == abbrev_offset)
+    if (list->raw == raw)
       return list;
 
   return NULL;
@@ -1040,6 +1037,7 @@ process_abbrev_set (struct dwarf_section *section,
   abbrev_list *list = xmalloc (sizeof (*list));
   list->first_abbrev = NULL;
   list->last_abbrev = NULL;
+  list->raw = start;
 
   while (start < end)
     {
@@ -1055,6 +1053,7 @@ process_abbrev_set (struct dwarf_section *section,
 	 the caller.  */
       if (start == end || entry == 0)
 	{
+	  list->next = NULL;
 	  list->start_of_next_abbrevs = start != end ? start : NULL;
 	  return list;
 	}
@@ -1144,16 +1143,10 @@ find_and_process_abbrev_set (struct dwarf_section *section,
   unsigned char *end = section->start + abbrev_base + abbrev_size;
   abbrev_list *list = NULL;
   if (free_list)
-    list = find_abbrev_list_by_abbrev_offset (abbrev_base, abbrev_offset);
+    list = find_abbrev_list_by_raw_abbrev (start);
   if (list == NULL)
     {
       list = process_abbrev_set (section, start, end);
-      if (list)
-	{
-	  list->abbrev_base = abbrev_base;
-	  list->abbrev_offset = abbrev_offset;
-	  list->next = NULL;
-	}
       if (free_list)
 	*free_list = list;
     }

-- 
Alan Modra
Australia Development Lab, IBM