xcoff slurp_armap bounds checking

[Alan Modra <amodra at gmail dot com>]

"count * 8 >= size" might overflow, "count >= size / 8" doesn't.

	* coff-rs6000.c (_bfd_xcoff_slurp_armap): Don't overflow when
	checking symbol count against section size.  Guard against strlen
	running off end of buffer by allocating one more byte and zeroing.
	* coff64-rs6000.c (xcoff64_slurp_armap): Likewise.

diff --git a/bfd/coff-rs6000.c b/bfd/coff-rs6000.c
index 86cf9e3e2a..995a88a309 100644
--- a/bfd/coff-rs6000.c
+++ b/bfd/coff-rs6000.c
@@ -1260,18 +1260,27 @@ _bfd_xcoff_slurp_armap (bfd *abfd)
 	return FALSE;
 
       GET_VALUE_IN_FIELD (sz, hdr.size, 10);
+      if (sz == (bfd_size_type) -1)
+	{
+	  bfd_set_error (bfd_error_no_memory);
+	  return FALSE;
+	}
 
       /* Read in the entire symbol table.  */
-      contents = (bfd_byte *) bfd_alloc (abfd, sz);
+      contents = (bfd_byte *) bfd_alloc (abfd, sz + 1);
       if (contents == NULL)
 	return FALSE;
       if (bfd_bread (contents, sz, abfd) != sz)
 	return FALSE;
 
+      /* Ensure strings are NULL terminated so we don't wander off the
+	 end of the buffer.  */
+      contents[sz] = 0;
+
       /* The symbol table starts with a four byte count.  */
       c = H_GET_32 (abfd, contents);
 
-      if (c * 4 >= sz)
+      if (c >= sz / 4)
 	{
 	  bfd_set_error (bfd_error_bad_value);
 	  return FALSE;
@@ -1315,18 +1324,27 @@ _bfd_xcoff_slurp_armap (bfd *abfd)
 	return FALSE;
 
       GET_VALUE_IN_FIELD (sz, hdr.size, 10);
+      if (sz == (bfd_size_type) -1)
+	{
+	  bfd_set_error (bfd_error_no_memory);
+	  return FALSE;
+	}
 
       /* Read in the entire symbol table.  */
-      contents = (bfd_byte *) bfd_alloc (abfd, sz);
+      contents = (bfd_byte *) bfd_alloc (abfd, sz + 1);
       if (contents == NULL)
 	return FALSE;
       if (bfd_bread (contents, sz, abfd) != sz)
 	return FALSE;
 
+      /* Ensure strings are NULL terminated so we don't wander off the
+	 end of the buffer.  */
+      contents[sz] = 0;
+
       /* The symbol table starts with an eight byte count.  */
       c = H_GET_64 (abfd, contents);
 
-      if (c * 8 >= sz)
+      if (c >= sz / 8)
 	{
 	  bfd_set_error (bfd_error_bad_value);
 	  return FALSE;
diff --git a/bfd/coff64-rs6000.c b/bfd/coff64-rs6000.c
index 091da1fd5e..4db61e5706 100644
--- a/bfd/coff64-rs6000.c
+++ b/bfd/coff64-rs6000.c
@@ -1933,18 +1933,27 @@ xcoff64_slurp_armap (bfd *abfd)
     return FALSE;
 
   sz = bfd_scan_vma (hdr.size, (const char **) NULL, 10);
+  if (sz == (bfd_size_type) -1)
+    {
+      bfd_set_error (bfd_error_no_memory);
+      return FALSE;
+    }
 
   /* Read in the entire symbol table.  */
-  contents = (bfd_byte *) bfd_alloc (abfd, sz);
+  contents = (bfd_byte *) bfd_alloc (abfd, sz + 1);
   if (contents == NULL)
     return FALSE;
   if (bfd_bread (contents, sz, abfd) != sz)
     return FALSE;
 
+  /* Ensure strings are NULL terminated so we don't wander off the end
+     of the buffer.  */
+  contents[sz] = 0;
+
   /* The symbol table starts with an eight byte count.  */
   c = H_GET_64 (abfd, contents);
 
-  if (c * 8 >= sz)
+  if (c >= sz / 8)
     {
       bfd_set_error (bfd_error_bad_value);
       return FALSE;

-- 
Alan Modra
Australia Development Lab, IBM