[binutils-gdb] Prevent looping in archives

[Alan Modra]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=4978e369fb75a8b7756bf4201668b2a9d9556286

commit 4978e369fb75a8b7756bf4201668b2a9d9556286
Author: Alan Modra <amodra@gmail.com>
Date:   Wed Nov 18 22:12:23 2015 +1030

    Prevent looping in archives
    
    	PR 19256
    	* archive.c (bfd_generic_openr_next_archived_file): Don't allow
    	backward file movement via "negative" sizes.
    	* coff-alpha.c (alpha_ecoff_openr_next_archived_file): Likewise.

Diff:
---
 bfd/ChangeLog    |  7 +++++++
 bfd/archive.c    | 24 ++++++++++++++++--------
 bfd/coff-alpha.c |  8 +++++++-
 3 files changed, 30 insertions(+), 9 deletions(-)

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 46a2caf..b70456d 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,10 @@
+2015-11-18  Alan Modra  <amodra@gmail.com>
+
+	PR 19256
+	* archive.c (bfd_generic_openr_next_archived_file): Don't allow
+	backward file movement via "negative" sizes.
+	* coff-alpha.c (alpha_ecoff_openr_next_archived_file): Likewise.
+
 2015-11-18  Tristan Gingold  <gingold@adacore.com>
 
 	* mach-o.h (struct mach_o_data_struct): Add hdr_offset field.
diff --git a/bfd/archive.c b/bfd/archive.c
index 1715474..b3d03d3 100644
--- a/bfd/archive.c
+++ b/bfd/archive.c
@@ -786,21 +786,29 @@ bfd_openr_next_archived_file (bfd *archive, bfd *last_file)
 bfd *
 bfd_generic_openr_next_archived_file (bfd *archive, bfd *last_file)
 {
-  file_ptr filestart;
+  ufile_ptr filestart;
 
   if (!last_file)
     filestart = bfd_ardata (archive)->first_file_filepos;
   else
     {
-      bfd_size_type size = arelt_size (last_file);
-
       filestart = last_file->proxy_origin;
       if (! bfd_is_thin_archive (archive))
-	filestart += size;
-      /* Pad to an even boundary...
-	 Note that last_file->origin can be odd in the case of
-	 BSD-4.4-style element with a long odd size.  */
-      filestart += filestart % 2;
+	{
+	  bfd_size_type size = arelt_size (last_file);
+
+	  filestart += size;
+	  /* Pad to an even boundary...
+	     Note that last_file->origin can be odd in the case of
+	     BSD-4.4-style element with a long odd size.  */
+	  filestart += filestart % 2;
+	  if (filestart <= last_file->proxy_origin)
+	    {
+	      /* Prevent looping.  See PR19256.  */
+	      bfd_set_error (bfd_error_malformed_archive);
+	      return NULL;
+	    }
+	}
     }
 
   return _bfd_get_elt_at_filepos (archive, filestart);
diff --git a/bfd/coff-alpha.c b/bfd/coff-alpha.c
index 58d4e1d..7478f2f 100644
--- a/bfd/coff-alpha.c
+++ b/bfd/coff-alpha.c
@@ -2187,7 +2187,7 @@ alpha_ecoff_get_elt_at_filepos (bfd *archive, file_ptr filepos)
 static bfd *
 alpha_ecoff_openr_next_archived_file (bfd *archive, bfd *last_file)
 {
-  file_ptr filestart;
+  ufile_ptr filestart;
 
   if (last_file == NULL)
     filestart = bfd_ardata (archive)->first_file_filepos;
@@ -2208,6 +2208,12 @@ alpha_ecoff_openr_next_archived_file (bfd *archive, bfd *last_file)
 	 BSD-4.4-style element with a long odd size.  */
       filestart = last_file->proxy_origin + size;
       filestart += filestart % 2;
+      if (filestart <= last_file->proxy_origin)
+	{
+	  /* Prevent looping.  See PR19256.  */
+	  bfd_set_error (bfd_error_malformed_archive);
+	  return NULL;
+	}
     }
 
   return alpha_ecoff_get_elt_at_filepos (archive, filestart);