[binutils-gdb] Limit bogus archive parsed_size

[Alan Modra]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=b570b954bc5c1d6a6edb363c7bdba814bc1fd174

commit b570b954bc5c1d6a6edb363c7bdba814bc1fd174
Author: Alan Modra <amodra@gmail.com>
Date:   Tue Feb 25 12:48:43 2020 +1030

    Limit bogus archive parsed_size
    
    Archive element size is given by data in the archive, and thus is
    subject to attack by fuzzers.  The only harm this allows is allocation
    of huge amounts of memory, but some systems don't handle that well.
    So limit archive element size to archive file size.
    
    	* bfdio.c (bfd_get_file_size): Ignore bogus archive element sizes.

Diff:
---
 bfd/ChangeLog |  4 ++++
 bfd/bfdio.c   | 18 ++++++++++++++++--
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 7e8e454..5855df7 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,7 @@
+2020-02-26  Alan Modra  <amodra@gmail.com>
+
+	* bfdio.c (bfd_get_file_size): Ignore bogus archive element sizes.
+
 2020-02-25  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR binutils/25584
diff --git a/bfd/bfdio.c b/bfd/bfdio.c
index 49e0958..71ac17e 100644
--- a/bfd/bfdio.c
+++ b/bfd/bfdio.c
@@ -25,6 +25,7 @@
 #include <limits.h>
 #include "bfd.h"
 #include "libbfd.h"
+#include "aout/ar.h"
 
 #ifndef S_IXUSR
 #define S_IXUSR 0100    /* Execute by owner.  */
@@ -460,11 +461,24 @@ DESCRIPTION
 ufile_ptr
 bfd_get_file_size (bfd *abfd)
 {
+  ufile_ptr file_size, archive_size = (ufile_ptr) -1;
+
   if (abfd->my_archive != NULL
       && !bfd_is_thin_archive (abfd->my_archive))
-    return arelt_size (abfd);
+    {
+      struct areltdata *adata = (struct areltdata *) abfd->arelt_data;
+      archive_size = adata->parsed_size;
+      /* If the archive is compressed we can't compare against file size.  */
+      if (memcmp (((struct ar_hdr *) adata->arch_header)->ar_fmag,
+		  "Z\012", 2) == 0)
+	return archive_size;
+      abfd = abfd->my_archive;
+    }
 
-  return bfd_get_size (abfd);
+  file_size = bfd_get_size (abfd);
+  if (archive_size < file_size)
+    return archive_size;
+  return file_size;
 }
 
 /*