pr22895

# DP: Catch integer overflows/underflows when parsing corrupt DWARF FORM blocks.

From 12c963421d045a127c413a0722062b9932c50aa9 Mon Sep 17 00:00:00 2001
From: Nick Clifton <nickc@redhat.com>
Date: Wed, 28 Feb 2018 11:50:49 +0000
Subject: [PATCH] Catch integer overflows/underflows when parsing corrupt DWARF
 FORM blocks.

	PR 22895
	PR 22893
	* dwarf2.c (read_n_bytes): Replace size parameter with dwarf_block
	pointer.  Drop unused abfd parameter.  Check the size of the block
	before initialising the data field.  Return the end pointer if the
	size is invalid.
	(read_attribute_value): Adjust invocations of read_n_bytes.

Gbp-Pq: Name pr22895.diff

diff --git a/bfd/dwarf2.c b/bfd/dwarf2.c
index a4a0dda209ecc1ee6a906b654185a9f8335f3ff1..e4f3714942d39932d874f317deb1383aa760c39f 100644 (file)
--- a/bfd/dwarf2.c
+++ b/bfd/dwarf2.c
@@ -622,14 +622,24 @@ read_8_bytes (bfd *abfd, bfd_byte *buf, bfd_byte *end)
 }
 
 static bfd_byte *
-read_n_bytes (bfd *abfd ATTRIBUTE_UNUSED,
-             bfd_byte *buf,
-             bfd_byte *end,
-             unsigned int size ATTRIBUTE_UNUSED)
+read_n_bytes (bfd_byte *           buf,
+             bfd_byte *           end,
+             struct dwarf_block * block)
 {
-  if (buf + size > end)
-    return NULL;
-  return buf;
+  unsigned int  size = block->size;
+  bfd_byte *    block_end = buf + size;
+
+  if (block_end > end || block_end < buf)
+    {
+      block->data = NULL;
+      block->size = 0;
+      return end;
+    }
+  else
+    {
+      block->data = buf;
+      return block_end;
+    }
 }
 
 /* Scans a NUL terminated string starting at BUF, returning a pointer to it.
@@ -1127,8 +1137,7 @@ read_attribute_value (struct attribute *  attr,
        return NULL;
       blk->size = read_2_bytes (abfd, info_ptr, info_ptr_end);
       info_ptr += 2;
-      blk->data = read_n_bytes (abfd, info_ptr, info_ptr_end, blk->size);
-      info_ptr += blk->size;
+      info_ptr = read_n_bytes (info_ptr, info_ptr_end, blk);
       attr->u.blk = blk;
       break;
     case DW_FORM_block4:
@@ -1138,8 +1147,7 @@ read_attribute_value (struct attribute *  attr,
        return NULL;
       blk->size = read_4_bytes (abfd, info_ptr, info_ptr_end);
       info_ptr += 4;
-      blk->data = read_n_bytes (abfd, info_ptr, info_ptr_end, blk->size);
-      info_ptr += blk->size;
+      info_ptr = read_n_bytes (info_ptr, info_ptr_end, blk);
       attr->u.blk = blk;
       break;
     case DW_FORM_data2:
@@ -1179,8 +1187,7 @@ read_attribute_value (struct attribute *  attr,
       blk->size = _bfd_safe_read_leb128 (abfd, info_ptr, &bytes_read,
                                         FALSE, info_ptr_end);
       info_ptr += bytes_read;
-      blk->data = read_n_bytes (abfd, info_ptr, info_ptr_end, blk->size);
-      info_ptr += blk->size;
+      info_ptr = read_n_bytes (info_ptr, info_ptr_end, blk);
       attr->u.blk = blk;
       break;
     case DW_FORM_block1:
@@ -1190,8 +1197,7 @@ read_attribute_value (struct attribute *  attr,
        return NULL;
       blk->size = read_1_byte (abfd, info_ptr, info_ptr_end);
       info_ptr += 1;
-      blk->data = read_n_bytes (abfd, info_ptr, info_ptr_end, blk->size);
-      info_ptr += blk->size;
+      info_ptr = read_n_bytes (info_ptr, info_ptr_end, blk);
       attr->u.blk = blk;
       break;
     case DW_FORM_data1: