From: Alan Modra <amodra@gmail.com>
Date: Mon, 23 Dec 2019 07:28:09 +0000 (+1030)
Subject: ubsan: wasm: shift is too large for 64-bit type 'bfd_vma'
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=27c1c4271a14cc2ebc27227212c19d4227ef212d;p=binutils-gdb.git

ubsan: wasm: shift is too large for 64-bit type 'bfd_vma'

bfd/
	* wasm-module.c (wasm_read_leb128): Don't allow oversize shifts.
	Catch value overflow.  Sign extend only on terminating byte.
opcodes/
	* wasm32-dis.c (wasm_read_leb128): Don't allow oversize shifts.
	Catch value overflow.  Sign extend only on terminating byte.
---

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 40f4b663642..8a2120ec2a2 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,8 @@
+2019-12-23  Alan Modra  <amodra@gmail.com>
+
+	* wasm-module.c (wasm_read_leb128): Don't allow oversize shifts.
+	Catch value overflow.  Sign extend only on terminating byte.
+
 2019-12-20  Alan Modra  <amodra@gmail.com>
 
 	* xtensa-isa.c (xtensa_insnbuf_from_chars): Avoid signed overflow.
diff --git a/bfd/wasm-module.c b/bfd/wasm-module.c
index a827d108ede..3fa2a87fb47 100644
--- a/bfd/wasm-module.c
+++ b/bfd/wasm-module.c
@@ -111,18 +111,28 @@ wasm_read_leb128 (bfd *		  abfd,
   unsigned int num_read = 0;
   unsigned int shift = 0;
   unsigned char byte = 0;
-  bfd_boolean success = FALSE;
+  int status = 1;
 
   while (bfd_bread (&byte, 1, abfd) == 1)
     {
       num_read++;
 
-      result |= ((bfd_vma) (byte & 0x7f)) << shift;
+      if (shift < sizeof (result) * 8)
+	{
+	  result |= ((bfd_vma) (byte & 0x7f)) << shift;
+	  if ((result >> shift) != (byte & 0x7f))
+	    /* Overflow.  */
+	    status |= 2;
+	  shift += 7;
+	}
+      else if ((byte & 0x7f) != 0)
+	status |= 2;
 
-      shift += 7;
       if ((byte & 0x80) == 0)
 	{
-	  success = TRUE;
+	  status &= ~1;
+	  if (sign && (shift < 8 * sizeof (result)) && (byte & 0x40))
+	    result |= -((bfd_vma) 1 << shift);
 	  break;
 	}
     }
@@ -130,10 +140,7 @@ wasm_read_leb128 (bfd *		  abfd,
   if (length_return != NULL)
     *length_return = num_read;
   if (error_return != NULL)
-    *error_return = ! success;
-
-  if (sign && (shift < 8 * sizeof (result)) && (byte & 0x40))
-    result |= -((bfd_vma) 1 << shift);
+    *error_return = status != 0;
 
   return result;
 }
diff --git a/opcodes/ChangeLog b/opcodes/ChangeLog
index d6d73111320..9315ddef7ad 100644
--- a/opcodes/ChangeLog
+++ b/opcodes/ChangeLog
@@ -1,3 +1,8 @@
+2019-12-23  Alan Modra  <amodra@gmail.com>
+
+	* wasm32-dis.c (wasm_read_leb128): Don't allow oversize shifts.
+	Catch value overflow.  Sign extend only on terminating byte.
+
 2019-12-20  Alan Modra  <amodra@gmail.com>
 
 	PR 25281
diff --git a/opcodes/wasm32-dis.c b/opcodes/wasm32-dis.c
index b1042793a5e..a885148c8bd 100644
--- a/opcodes/wasm32-dis.c
+++ b/opcodes/wasm32-dis.c
@@ -192,29 +192,36 @@ wasm_read_leb128 (bfd_vma                   pc,
   unsigned int num_read = 0;
   unsigned int shift = 0;
   unsigned char byte = 0;
-  bfd_boolean success = FALSE;
+  int status = 1;
 
   while (info->read_memory_func (pc + num_read, &byte, 1, info) == 0)
     {
       num_read++;
 
-      result |= ((bfd_vma) (byte & 0x7f)) << shift;
+      if (shift < sizeof (result) * 8)
+	{
+	  result |= ((uint64_t) (byte & 0x7f)) << shift;
+	  if ((result >> shift) != (byte & 0x7f))
+	    /* Overflow.  */
+	    status |= 2;
+	  shift += 7;
+	}
+      else if ((byte & 0x7f) != 0)
+	status |= 2;
 
-      shift += 7;
       if ((byte & 0x80) == 0)
-        {
-          success = TRUE;
-          break;
-        }
+	{
+	  status &= ~1;
+	  if (sign && (shift < 8 * sizeof (result)) && (byte & 0x40))
+	    result |= -((uint64_t) 1 << shift);
+	  break;
+	}
     }
 
   if (length_return != NULL)
     *length_return = num_read;
   if (error_return != NULL)
-    *error_return = ! success;
-
-  if (sign && (shift < 8 * sizeof (result)) && (byte & 0x40))
-    result |= -((uint64_t) 1 << shift);
+    *error_return = status != 0;
 
   return result;
 }