From: Matt Birkholz <puck@birchwood-abbey.net>
Date: Fri, 29 Jan 2016 19:46:44 +0000 (-0700)
Subject: debug.c (verify_heap, dump_heap_at): Avoid SIGSEGVing.
X-Git-Tag: mit-scheme-pucked-9.2.12~371^2~6
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=88e2ac8c48d5ca379ac31dcb17b4687037bea9c3;p=mit-scheme.git

debug.c (verify_heap, dump_heap_at): Avoid SIGSEGVing.

Check that all pointers and block offsets are valid heap addresses
before following them.  Do not dump words past Free (in bogus objects
at the end of the heap).
---

diff --git a/src/microcode/debug.c b/src/microcode/debug.c
index 5f14249e8..573e68e3d 100644
--- a/src/microcode/debug.c
+++ b/src/microcode/debug.c
@@ -806,9 +806,13 @@ dump_object (SCHEME_OBJECT * addr)
   outf_error ("\n");
   {
     SCHEME_OBJECT * end = next_addr (addr);
+    if (end > Free)
+      end = Free;
     while (++addr < end)
       dump_word (addr);
   }
+  if (addr == Free)
+    outf_error ("%#lx: Free\n", (unsigned long)addr);
 }
 
 #define SAVE_COUNT 16
@@ -885,21 +889,25 @@ verify_object (SCHEME_OBJECT object)
    || ((heap_start <= (address)) && ((address) < Free)))
 
 static bool
-verify_tuple (SCHEME_OBJECT object, int size, SCHEME_OBJECT * address)
+verify_tuple (SCHEME_OBJECT object, int size, const char * name,
+	      unsigned long address)
 {
-  int i = 0;
+  SCHEME_OBJECT * location;
+  int i;
+
+  location = OBJECT_ADDRESS (object);
+  if (! (VALID_ADDRESS_P (location)))
+    {
+      outf_error ("%#lx: Invalid %s\n", address, name);
+      return (false);
+    }
+  i = 0;
   while (i < size)
     {
       SCHEME_OBJECT * slot = MEMORY_LOC (object, i);
       if (! ((VALID_ADDRESS_P (slot)) && verify_object (*slot)))
 	{
-	  outf_error ("%#lx: Invalid %s\n",
-		      (unsigned long)address,
-		      (size == 1 ? "cell"
-		       : size == 2 ? "pair"
-		       : size == 3 ? "triple"
-		       : size == 4 ? "quadruple"
-		       : "tuple"));
+	  outf_error ("%#lx: Invalid %s (word %d)\n", address, name, i);
 	  return (false);
 	}
       i += 1;
@@ -908,50 +916,92 @@ verify_tuple (SCHEME_OBJECT object, int size, SCHEME_OBJECT * address)
 }
 
 static bool
-verify_vector (SCHEME_OBJECT object, SCHEME_OBJECT * address)
+verify_vector (SCHEME_OBJECT object, unsigned long address)
 {
-  unsigned long header = MEMORY_REF(object, 0);
-  unsigned long length = OBJECT_DATUM(header);
-  unsigned int header_type = OBJECT_TYPE (header);
+  unsigned long header, length;
+  unsigned int header_type;
+  SCHEME_OBJECT * location;
+
+  location = OBJECT_ADDRESS (object);
+  if (! (VALID_ADDRESS_P (location)))
+    {
+      outf_error ("%#lx: Invalid vector\n", address);
+      return (false);
+    }
+  header = MEMORY_REF (object, 0);
+  length = OBJECT_DATUM (header);
+  header_type = OBJECT_TYPE (header);
   if (header_type != TC_MANIFEST_VECTOR
       && header_type != TC_MANIFEST_NM_VECTOR)
     {
-      outf_error ("%#lx: Invalid vector\n", (unsigned long)address);
+      outf_error ("%#lx: Invalid vector header\n", address);
       return (false);
     }
+  if (! (VALID_ADDRESS_P (location + length)))
+    {
+      outf_error ("%#lx: Invalid vector length\n", address);
+      return (false);
+    }
+  /* Double-check each element? */
   if (length > 1000000)
     {
-      outf_error ("%#lx: Extraordinary vector size %ld\n",
-		  (unsigned long)address, length);
+      outf_error ("%#lx: Extraordinary vector size: %ld\n", address, length);
     }
   return (true);
 }
 
 #ifdef CC_SUPPORT_P
 static bool
-verify_compiled (SCHEME_OBJECT object, SCHEME_OBJECT * address)
+verify_compiled (SCHEME_OBJECT object, unsigned long address)
 {
-  SCHEME_OBJECT * block;
-  SCHEME_OBJECT header;
-  unsigned int header_type;
+  insn_t * block;
+
   if (! (VALID_ADDRESS_P (OBJECT_ADDRESS (object))))
     {
-      outf_error ("%#lx: Invalid entry\n", (unsigned long)address);
-      return (false);
-    }
-  block = cc_entry_to_block_address (object);
-  if (! (VALID_ADDRESS_P (block)))
-    {
-      outf_error ("%#lx: Invalid entry block\n", (unsigned long)address);
+      outf_error ("%#lx: Invalid entry\n", address);
       return (false);
     }
-  header = *block;
-  header_type = OBJECT_TYPE(header);
-  if (! (header_type == TC_MANIFEST_VECTOR
-	 || header_type == TC_MANIFEST_CLOSURE))
+  /* block = cc_entry_to_block_address (object);  too many SIGSEGVs! */
+  block = CC_ENTRY_ADDRESS (object);
+  while (1)
     {
-      outf_error ("%#lx: Invalid entry block header\n", (unsigned long)address);
-      return (false);
+      cc_entry_offset_t ceo;
+      if (read_cc_entry_offset ((&ceo), block))
+	{
+	  outf_error ("%#lx: Invalid entry format\n", address);
+	  return (false);
+	}
+      assert (ceo.offset > 0);
+      block -= (ceo.offset);
+      if (! (VALID_ADDRESS_P ((SCHEME_OBJECT *)block)))
+	{
+	  outf_error ("%#lx: Invalid entry offset\n", address);
+	  return (false);
+	}
+      if (! (ceo.continued_p))
+	{
+	  unsigned int header_type;
+
+	  if ((unsigned long)block % sizeof (SCHEME_OBJECT) != 0)
+	    {
+	      outf_error ("%#lx: Invalid block alignment\n", address);
+	      return (false);
+	    }
+	  if ((CC_BLOCK_ADDR_END ((SCHEME_OBJECT *) block))
+	      < ((SCHEME_OBJECT *) (CC_ENTRY_ADDRESS (object))))
+	    {
+	      outf_error ("%#lx: Invalid block size\n", address);
+	      return (false);
+	    }
+	  header_type = OBJECT_TYPE(*block);
+	  if (! (header_type == TC_MANIFEST_VECTOR
+		 || header_type == TC_MANIFEST_CLOSURE))
+	    {
+	      outf_error ("%#lx: Invalid block header\n", address);
+	      return (false);
+	    }
+	  break;
+	}
     }
   return (true);
 }
@@ -981,31 +1031,31 @@ verify_heap_area (const char * name, SCHEME_OBJECT * area, SCHEME_OBJECT * end)
 	  break;
 
 	case GC_CELL:
-	  if (! verify_tuple (object, 1, area))
+	  if (! verify_tuple (object, 1, "cell", (unsigned long)area))
 	    complaints += 1;
 	  area += 1;
 	  break;
 
 	case GC_PAIR:
-	  if (! verify_tuple (object, 2, area))
+	  if (! verify_tuple (object, 2, "pair", (unsigned long)area))
 	    complaints += 1;
 	  area += 1;
 	  break;
 
 	case GC_TRIPLE:
-	  if (! verify_tuple (object, 3, area))
+	  if (! verify_tuple (object, 3, "triple", (unsigned long)area))
 	    complaints += 1;
 	  area += 1;
 	  break;
 
 	case GC_QUADRUPLE:
-	  if (! verify_tuple (object, 4, area))
+	  if (! verify_tuple (object, 4, "quadruple", (unsigned long)area))
 	    complaints += 1;
 	  area += 1;
 	  break;
 
 	case GC_VECTOR:
-	  if (! verify_vector (object, area))
+	  if (! verify_vector (object, (unsigned long)area))
 	    complaints += 1;
 	  area += 1;
 	  break;
@@ -1050,14 +1100,14 @@ verify_heap_area (const char * name, SCHEME_OBJECT * area, SCHEME_OBJECT * end)
 		      SCHEME_OBJECT * next = area + (1 + n_words);
 		      if (next > end)
 			{
-			  outf_error ("%#lx: Invalid linkage section size %ld\n",
+			  outf_error ("%#lx: Invalid linkage section size: %ld\n",
 				      (unsigned long)area, n_words);
 			  return (false);
 			}
 		      else if (n_words > 1000)
 			{
 			  outf_error
-			    ("%#lx: Extraordinary linkage section size %ld\n",
+			    ("%#lx: Extraordinary linkage section size: %ld\n",
 			     (unsigned long)area, n_words);
 			}
 		      area = next;
@@ -1068,7 +1118,7 @@ verify_heap_area (const char * name, SCHEME_OBJECT * area, SCHEME_OBJECT * end)
 		    area += 1;
 		    break;
 		  default:
-		    outf_error ("%#lx: Invalid linkage section type %#x\n",
+		    outf_error ("%#lx: Invalid linkage section type: %#x\n",
 				(unsigned long)area, section_type);
 		    complaints += 1;
 		    area += 1;
@@ -1087,13 +1137,13 @@ verify_heap_area (const char * name, SCHEME_OBJECT * area, SCHEME_OBJECT * end)
 		SCHEME_OBJECT * next = area + (1 + n_words);
 		if (next > end)
 		  {
-		    outf_error ("%#lx: Invalid nm-vector size %ld\n",
+		    outf_error ("%#lx: Invalid nm-vector size: %ld\n",
 				(unsigned long)area, n_words);
 		    return (false);
 		  }
 		else if (n_words > 1000000)
 		  {
-		    outf_error ("%#lx: Extraordinary nm-vector size %ld\n",
+		    outf_error ("%#lx: Extraordinary nm-vector size: %ld\n",
 				(unsigned long)area, n_words);
 		  }
 		area = next;
@@ -1110,14 +1160,14 @@ verify_heap_area (const char * name, SCHEME_OBJECT * area, SCHEME_OBJECT * end)
 
 #ifdef CC_SUPPORT_P
 	case GC_COMPILED:
-	  if (! verify_compiled (object, area))
+	  if (! verify_compiled (object, (unsigned long)area))
 	    complaints += 1;
 	  area += 1;
 	  break;
 #endif
 
 	default:
-	  outf_error ("%#lx: unknown gc type code %#x\n",
+	  outf_error ("%#lx: unknown gc type code: %#x\n",
 		      (unsigned long)area, gc_type_code (type));
 	  complaints += 1;
 	}