PR22216, infinite loop in readelf process_symbol_table

[Alan Modra <amodra at gmail dot com>]

This should make readelf bombproof given a fuzzed DT_HASH.  Also
removes a bogus check that would have resulted in wrong histograms.

	PR 22216
	* readelf.c (process_symbol_table): Check that DT_HASH symbol
	chains are only visited once, and report an error if not.  Display
	invalid symbol index if chain is out of range.  Use the same logic
	when calculating histograms rather than the PR 17531 fix.  Delete
	bogus check that chained index is less than number of buckets.

diff --git a/binutils/readelf.c b/binutils/readelf.c
index 3e5ad0e..260aedf 100644
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -11436,6 +11436,7 @@ process_symbol_table (FILE * file)
       if (dynamic_info[DT_HASH])
 	{
 	  bfd_vma si;
+	  char *visited;
 
 	  printf (_("\nSymbol table for image:\n"));
 	  if (is_32bit_elf)
@@ -11443,14 +11444,22 @@ process_symbol_table (FILE * file)
 	  else
 	    printf (_("  Num Buc:    Value          Size   Type   Bind Vis      Ndx Name\n"));
 
+	  visited = xcmalloc (nchains, 1);
+	  memset (visited, 0, nchains);
 	  for (hn = 0; hn < nbuckets; hn++)
 	    {
-	      if (! buckets[hn])
-		continue;
-
-	      for (si = buckets[hn]; si < nchains && si > 0; si = chains[si])
-		print_dynamic_symbol (si, hn);
+	      for (si = buckets[hn]; si > 0; si = chains[si])
+		{
+		  print_dynamic_symbol (si, hn);
+		  if (si >= nchains || visited[si])
+		    {
+		      error (_("histogram chain is corrupt\n"));
+		      break;
+		    }
+		  visited[si] = 1;
+		}
 	    }
+	  free (visited);
 	}
 
       if (dynamic_info_DT_GNU_HASH)
@@ -11609,7 +11618,7 @@ process_symbol_table (FILE * file)
       unsigned long maxlength = 0;
       unsigned long nzero_counts = 0;
       unsigned long nsyms = 0;
-      unsigned long chained;
+      char *visited;
 
       printf (_("\nHistogram for bucket list length (total of %lu buckets):\n"),
 	      (unsigned long) nbuckets);
@@ -11620,28 +11629,26 @@ process_symbol_table (FILE * file)
 	  error (_("Out of memory allocating space for histogram buckets\n"));
 	  return FALSE;
 	}
+      visited = xcmalloc (nchains, 1);
+      memset (visited, 0, nchains);
 
       printf (_(" Length  Number     %% of total  Coverage\n"));
       for (hn = 0; hn < nbuckets; ++hn)
 	{
-	  for (si = buckets[hn], chained = 0;
-	       si > 0 && si < nchains && si < nbuckets && chained <= nchains;
-	       si = chains[si], ++chained)
+	  for (si = buckets[hn]; si > 0; si = chains[si])
 	    {
 	      ++nsyms;
 	      if (maxlength < ++lengths[hn])
 		++maxlength;
+	      if (si >= nchains || visited[si])
+		{
+		  error (_("histogram chain is corrupt\n"));
+		  break;
+		}
+	      visited[si] = 1;
 	    }
-
-	    /* PR binutils/17531: A corrupt binary could contain broken
-	       histogram data.  Do not go into an infinite loop trying
-	       to process it.  */
-	    if (chained > nchains)
-	      {
-		error (_("histogram chain is corrupt\n"));
-		break;
-	      }
 	}
+      free (visited);
 
       counts = (unsigned long *) calloc (maxlength + 1, sizeof (*counts));
       if (counts == NULL)

-- 
Alan Modra
Australia Development Lab, IBM