[binutils-gdb] Prevent a memory exhaustion failure when running objdump on a fuzzed input file with corrupt string

[Nick Clifton <nickc at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=95a6d23566165208853a68d9cd3c6eedca840ec6

commit 95a6d23566165208853a68d9cd3c6eedca840ec6
Author: Nick Clifton <nickc@redhat.com>
Date:   Tue May 8 12:51:06 2018 +0100

    Prevent a memory exhaustion failure when running objdump on a fuzzed input file with corrupt string and attribute sections.
    
    	PR 22809
    	* elf.c (bfd_elf_get_str_section): Check for an excessively large
    	string section.
    	* elf-attrs.c (_bfd_elf_parse_attributes): Issue an error if the
    	attribute section is larger than the size of the file.

Diff:
---
 bfd/ChangeLog   | 8 ++++++++
 bfd/elf-attrs.c | 9 +++++++++
 bfd/elf.c       | 1 +
 3 files changed, 18 insertions(+)

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index d26c69a..e478821 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,11 @@
+2018-05-08  Nick Clifton  <nickc@redhat.com>
+
+	PR 22809
+	* elf.c (bfd_elf_get_str_section): Check for an excessively large
+	string section.
+	* elf-attrs.c (_bfd_elf_parse_attributes): Issue an error if the
+	attribute section is larger than the size of the file.
+
 2018-05-07  Alan Modra  <amodra@gmail.com>
 
 	* cofflink.c (_bfd_coff_link_input_bfd): Use memcmp rather than
diff --git a/bfd/elf-attrs.c b/bfd/elf-attrs.c
index dfdf1a5..b353309 100644
--- a/bfd/elf-attrs.c
+++ b/bfd/elf-attrs.c
@@ -438,6 +438,15 @@ _bfd_elf_parse_attributes (bfd *abfd, Elf_Internal_Shdr * hdr)
   /* PR 17512: file: 2844a11d.  */
   if (hdr->sh_size == 0)
     return;
+  if (hdr->sh_size > bfd_get_file_size (abfd))
+    {
+      /* xgettext:c-format */
+      _bfd_error_handler (_("%pB: error: attribute section '%pA' too big: %#llx"),
+			  abfd, hdr->bfd_section, (long long) hdr->sh_size);
+      bfd_set_error (bfd_error_invalid_operation);
+      return;
+    }
+
   contents = (bfd_byte *) bfd_malloc (hdr->sh_size + 1);
   if (!contents)
     return;
diff --git a/bfd/elf.c b/bfd/elf.c
index 21bc4e7..3e8d510 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -298,6 +298,7 @@ bfd_elf_get_str_section (bfd *abfd, unsigned int shindex)
       /* Allocate and clear an extra byte at the end, to prevent crashes
 	 in case the string table is not terminated.  */
       if (shstrtabsize + 1 <= 1
+	  || shstrtabsize > bfd_get_file_size (abfd)
 	  || bfd_seek (abfd, offset, SEEK_SET) != 0
 	  || (shstrtab = (bfd_byte *) bfd_alloc (abfd, shstrtabsize + 1)) == NULL)
 	shstrtab = NULL;