Re: H8300 use of uninitialised value

This patch also had some problems.  Calculation of maxlen was wrong,
and the insn arg loop needed rearranging to work with a correct length.

	* disassemble.h (opcodes_assert): Declare.
	(OPCODES_ASSERT): Define.
	* disassemble.c: Don't include assert.h.  Include opintl.h.
	(opcodes_assert): New function.
	* h8300-dis.c (bfd_h8_disassemble_init): Use OPCODES_ASSERT.
	(bfd_h8_disassemble): Reduce size of data array.  Correctly
	calculate maxlen.  Omit insn decoding when insn length exceeds
	maxlen.  Exit from nibble loop when looking for E, before
	accessing next data byte.  Move processing of E outside loop.
	Replace tests of maxlen in loop with assertions.

4 files changed, 152 insertions, 126 deletions

diff --git a/opcodes/ChangeLog b/opcodes/ChangeLog
index a88a762..17e3417 100644
--- a/opcodes/ChangeLog
+++ b/opcodes/ChangeLog
@@ -1,5 +1,18 @@
 2020-03-26  Alan Modra  <amodra@gmail.com>
 
+	* disassemble.h (opcodes_assert): Declare.
+	(OPCODES_ASSERT): Define.
+	* disassemble.c: Don't include assert.h.  Include opintl.h.
+	(opcodes_assert): New function.
+	* h8300-dis.c (bfd_h8_disassemble_init): Use OPCODES_ASSERT.
+	(bfd_h8_disassemble): Reduce size of data array.  Correctly
+	calculate maxlen.  Omit insn decoding when insn length exceeds
+	maxlen.  Exit from nibble loop when looking for E, before
+	accessing next data byte.  Move processing of E outside loop.
+	Replace tests of maxlen in loop with assertions.
+
+2020-03-26  Alan Modra  <amodra@gmail.com>
+
 	* arc-dis.c (find_format): Init needs_limm.  Simplify use of limm.
 
 2020-03-25  Alan Modra  <amodra@gmail.com>
diff --git a/opcodes/disassemble.c b/opcodes/disassemble.c
index d49a2b8..25816ef 100644
--- a/opcodes/disassemble.c
+++ b/opcodes/disassemble.c
@@ -21,7 +21,7 @@
 #include "sysdep.h"
 #include "disassemble.h"
 #include "safe-ctype.h"
-#include <assert.h>
+#include "opintl.h"
 
 #ifdef ARCH_all
 #define ARCH_aarch64
@@ -832,3 +832,11 @@ disassembler_options_cmp (const char *s1, const char *s2)
 
   return c1 - c2;
 }
+
+void
+opcodes_assert (const char *file, int line)
+{
+  opcodes_error_handler (_("assertion fail %s:%d"), file, line);
+  opcodes_error_handler (_("Please report this bug"));
+  abort ();
+}
diff --git a/opcodes/disassemble.h b/opcodes/disassemble.h
index 0365176..89db886 100644
--- a/opcodes/disassemble.h
+++ b/opcodes/disassemble.h
@@ -103,4 +103,10 @@ extern int print_insn_z8002		(bfd_vma, disassemble_info *);
 
 extern disassembler_ftype csky_get_disassembler (bfd *);
 extern disassembler_ftype rl78_get_disassembler (bfd *);
+
+extern void ATTRIBUTE_NORETURN opcodes_assert (const char *, int);
+
+#define OPCODES_ASSERT(x) \
+  do { if (!(x)) opcodes_assert (__FILE__, __LINE__); } while (0)
+
 #endif /* DISASSEMBLE_H */
diff --git a/opcodes/h8300-dis.c b/opcodes/h8300-dis.c
index f5e00c4..f56ad86 100644
--- a/opcodes/h8300-dis.c
+++ b/opcodes/h8300-dis.c
@@ -29,7 +29,7 @@
 
 struct h8_instruction
 {
-  int length;
+  unsigned int length;
   const struct h8_opcode *opcode;
 };
 
@@ -56,13 +56,7 @@ bfd_h8_disassemble_init (void)
 	 that the count is the same as the length.  */
       for (i = 0; p->data.nib[i] != (op_type) E; i++)
 	;
-
-      if (i & 1)
-	{
-	  /* xgettext:c-format */
-	  opcodes_error_handler (_("internal error, h8_disassemble_init"));
-	  abort ();
-	}
+      OPCODES_ASSERT (!(i & 1));
 
       pi->length = i / 2;
       pi->opcode = p;
@@ -328,7 +322,7 @@ bfd_h8_disassemble (bfd_vma addr, disassemble_info *info, int mach)
   char const **pregnames = mach != 0 ? lregnames : wregnames;
   int status;
   unsigned int maxlen;
-  unsigned char data[MAX_CODE_NIBBLES];
+  unsigned char data[MAX_CODE_NIBBLES / 2];
   void *stream = info->stream;
   fprintf_ftype outfn = info->fprintf_func;
 
@@ -345,22 +339,34 @@ bfd_h8_disassemble (bfd_vma addr, disassemble_info *info, int mach)
       return -1;
     }
 
-  for (maxlen = 2; status == 0 && maxlen < sizeof (data) / 2; maxlen += 2)
-    status = info->read_memory_func (addr + maxlen, data + maxlen, 2, info);
+  for (maxlen = 2; maxlen < sizeof (data); maxlen += 2)
+    {
+      status = info->read_memory_func (addr + maxlen, data + maxlen, 2, info);
+      if (status != 0)
+	break;
+    }
 
   /* Find the exact opcode/arg combo.  */
   for (qi = h8_instructions; qi->opcode->name; qi++)
     {
-      const struct h8_opcode *q = qi->opcode;
-      const op_type *nib = q->data.nib;
-      unsigned int len = 0;
-
-      while (len / 2 < maxlen)
+      const struct h8_opcode *q;
+      const op_type *nib;
+      unsigned int len;
+      op_type looking_for;
+
+      if (qi->length > maxlen)
+	continue;
+
+      q = qi->opcode;
+      nib = q->data.nib;
+      len = 0;
+      while ((looking_for = *nib) != (op_type) E)
 	{
-	  op_type looking_for = *nib;
-	  int thisnib = data[len / 2];
+	  int thisnib;
 	  int opnr;
 
+	  OPCODES_ASSERT (len / 2 < maxlen);
+	  thisnib = data[len / 2];
 	  thisnib = (len & 1) ? (thisnib & 0xf) : ((thisnib / 16) & 0xf);
 	  opnr = ((looking_for & OP3) == OP3 ? 2
 		  : (looking_for & DST) == DST ? 1 : 0);
@@ -476,8 +482,7 @@ bfd_h8_disassemble (bfd_vma addr, disassemble_info *info, int mach)
 		      extra = 0;
 		      break;
 		    }
-		  if (len / 2 + extra >= maxlen)
-		    break;
+		  OPCODES_ASSERT (len / 2 + extra < maxlen);
 		  extract_immediate (stream, looking_for, thisnib,
 				     data + len / 2, cst + opnr,
 				     cstlen + opnr, q);
@@ -532,8 +537,7 @@ bfd_h8_disassemble (bfd_vma addr, disassemble_info *info, int mach)
 	      else if ((looking_for & SIZE) == L_16
 		       || (looking_for & SIZE) == L_16U)
 		{
-		  if (len / 2 + 1 >= maxlen)
-		    break;
+		  OPCODES_ASSERT (len / 2 + 1 < maxlen);
 		  cst[opnr] = (data[len / 2]) * 256 + data[(len + 2) / 2];
 		  cstlen[opnr] = 16;
 		}
@@ -549,8 +553,7 @@ bfd_h8_disassemble (bfd_vma addr, disassemble_info *info, int mach)
 		{
 		  unsigned int i = len / 2;
 
-		  if (i + 3 >= maxlen)
-		    break;
+		  OPCODES_ASSERT (i + 3 < maxlen);
 		  cst[opnr] = (((unsigned) data[i] << 24)
 			       | (data[i + 1] << 16)
 			       | (data[i + 2] << 8)
@@ -562,8 +565,7 @@ bfd_h8_disassemble (bfd_vma addr, disassemble_info *info, int mach)
 		{
 		  unsigned int i = len / 2;
 
-		  if (i + 2 >= maxlen)
-		    break;
+		  OPCODES_ASSERT (i + 2 < maxlen);
 		  cst[opnr] =
 		    (data[i] << 16) | (data[i + 1] << 8) | (data[i + 2]);
 		  cstlen[opnr] = 24;
@@ -610,105 +612,6 @@ bfd_h8_disassemble (bfd_vma addr, disassemble_info *info, int mach)
 		{
 		  cst[opnr] = (thisnib == 3);
 		}
-	      else if (looking_for == (op_type) E)
-		{
-		  outfn (stream, "%s\t", q->name);
-
-		  /* Gross.  Disgusting.  */
-		  if (strcmp (q->name, "ldm.l") == 0)
-		    {
-		      int count, high;
-
-		      count = (data[1] / 16) & 0x3;
-		      high = regno[1];
-
-		      outfn (stream, "@sp+,er%d-er%d", high - count, high);
-		      return qi->length;
-		    }
-
-		  if (strcmp (q->name, "stm.l") == 0)
-		    {
-		      int count, low;
-
-		      count = (data[1] / 16) & 0x3;
-		      low = regno[0];
-
-		      outfn (stream, "er%d-er%d,@-sp", low, low + count);
-		      return qi->length;
-		    }
-		  if (strcmp (q->name, "rte/l") == 0
-		      || strcmp (q->name, "rts/l") == 0)
-		    {
-		      if (regno[0] == 0)
-			outfn (stream, "er%d", regno[1]);
-		      else
-			outfn (stream, "er%d-er%d", regno[1] - regno[0],
-			       regno[1]);
-		      return qi->length;
-		    }
-		  if (CONST_STRNEQ (q->name, "mova"))
-		    {
-		      const op_type *args = q->args.nib;
-
-		      if (args[1] == (op_type) E)
-			{
-			  /* Short form.  */
-			  print_one_arg (info, addr, args[0], cst[0],
-					 cstlen[0], dispregno[0], regno[0],
-					 pregnames, qi->length);
-			  outfn (stream, ",er%d", dispregno[0]);
-			}
-		      else
-			{
-			  outfn (stream, "@(0x%x:%d,", cst[0], cstlen[0]);
-			  print_one_arg (info, addr, args[1], cst[1],
-					 cstlen[1], dispregno[1], regno[1],
-					 pregnames, qi->length);
-			  outfn (stream, ".%c),",
-				 (args[0] & MODE) == INDEXB ? 'b' : 'w');
-			  print_one_arg (info, addr, args[2], cst[2],
-					 cstlen[2], dispregno[2], regno[2],
-					 pregnames, qi->length);
-			}
-		      return qi->length;
-		    }
-		  /* Fill in the args.  */
-		  {
-		    const op_type *args = q->args.nib;
-		    int hadone = 0;
-		    int nargs;
-
-		    /* Special case handling for the adds and subs instructions
-		       since in H8 mode thay can only take the r0-r7 registers
-		       but in other (higher) modes they can take the er0-er7
-		       registers as well.  */
-		    if (strcmp (qi->opcode->name, "adds") == 0
-			|| strcmp (qi->opcode->name, "subs") == 0)
-		      {
-			outfn (stream, "#%d,%s", cst[0], pregnames[regno[1] & 0x7]);
-			return qi->length;
-		      }
-
-		    for (nargs = 0;
-			 nargs < 3 && args[nargs] != (op_type) E;
-			 nargs++)
-		      {
-			int x = args[nargs];
-
-			if (hadone)
-			  outfn (stream, ",");
-
-			print_one_arg (info, addr, x,
-				       cst[nargs], cstlen[nargs],
-				       dispregno[nargs], regno[nargs],
-				       pregnames, qi->length);
-
-			hadone = 1;
-		      }
-		  }
-
-		  return qi->length;
-		}
 	      else
 		/* xgettext:c-format */
 		outfn (stream, _("Don't understand 0x%x \n"), looking_for);
@@ -718,6 +621,102 @@ bfd_h8_disassemble (bfd_vma addr, disassemble_info *info, int mach)
 	  nib++;
 	}
 
+      outfn (stream, "%s\t", q->name);
+
+      /* Gross.  Disgusting.  */
+      if (strcmp (q->name, "ldm.l") == 0)
+	{
+	  int count, high;
+
+	  count = (data[1] / 16) & 0x3;
+	  high = regno[1];
+
+	  outfn (stream, "@sp+,er%d-er%d", high - count, high);
+	  return qi->length;
+	}
+
+      if (strcmp (q->name, "stm.l") == 0)
+	{
+	  int count, low;
+
+	  count = (data[1] / 16) & 0x3;
+	  low = regno[0];
+
+	  outfn (stream, "er%d-er%d,@-sp", low, low + count);
+	  return qi->length;
+	}
+      if (strcmp (q->name, "rte/l") == 0
+	  || strcmp (q->name, "rts/l") == 0)
+	{
+	  if (regno[0] == 0)
+	    outfn (stream, "er%d", regno[1]);
+	  else
+	    outfn (stream, "er%d-er%d", regno[1] - regno[0],
+		   regno[1]);
+	  return qi->length;
+	}
+      if (CONST_STRNEQ (q->name, "mova"))
+	{
+	  const op_type *args = q->args.nib;
+
+	  if (args[1] == (op_type) E)
+	    {
+	      /* Short form.  */
+	      print_one_arg (info, addr, args[0], cst[0],
+			     cstlen[0], dispregno[0], regno[0],
+			     pregnames, qi->length);
+	      outfn (stream, ",er%d", dispregno[0]);
+	    }
+	  else
+	    {
+	      outfn (stream, "@(0x%x:%d,", cst[0], cstlen[0]);
+	      print_one_arg (info, addr, args[1], cst[1],
+			     cstlen[1], dispregno[1], regno[1],
+			     pregnames, qi->length);
+	      outfn (stream, ".%c),",
+		     (args[0] & MODE) == INDEXB ? 'b' : 'w');
+	      print_one_arg (info, addr, args[2], cst[2],
+			     cstlen[2], dispregno[2], regno[2],
+			     pregnames, qi->length);
+	    }
+	  return qi->length;
+	}
+      /* Fill in the args.  */
+      {
+	const op_type *args = q->args.nib;
+	int hadone = 0;
+	int nargs;
+
+	/* Special case handling for the adds and subs instructions
+	   since in H8 mode thay can only take the r0-r7 registers
+	   but in other (higher) modes they can take the er0-er7
+	   registers as well.  */
+	if (strcmp (qi->opcode->name, "adds") == 0
+	    || strcmp (qi->opcode->name, "subs") == 0)
+	  {
+	    outfn (stream, "#%d,%s", cst[0], pregnames[regno[1] & 0x7]);
+	    return qi->length;
+	  }
+
+	for (nargs = 0;
+	     nargs < 3 && args[nargs] != (op_type) E;
+	     nargs++)
+	  {
+	    int x = args[nargs];
+
+	    if (hadone)
+	      outfn (stream, ",");
+
+	    print_one_arg (info, addr, x,
+			   cst[nargs], cstlen[nargs],
+			   dispregno[nargs], regno[nargs],
+			   pregnames, qi->length);
+
+	    hadone = 1;
+	  }
+      }
+      return qi->length;
+
     fail:
       ;
     }