Partially fix CVE-2014-9112, part 1/5.  Backported to 2.11.

From 746f3ff670dcfcdd28fcc990e79cd6fccc7ae48d Mon Sep 17 00:00:00 2001
From: Sergey Poznyakoff <gray@gnu.org.ua>
Date: Mon, 01 Dec 2014 13:15:28 +0000
Subject: Fix memory overrun on reading improperly created link records.

See http://lists.gnu.org/archive/html/bug-cpio/2014-11/msg00007.html

* src/copyin.c (get_link_name): New function.
(list_file, copyin_link): use get_link_name

* tests/symlink-bad-length.at: New file.
* tests/symlink-long.at: New file.
* tests/Makefile.am: Add new files.
* tests/testsuite.at: Likewise.
---
diff --git a/src/copyin.c b/src/copyin.c
index 38d809f..c502c7d 100644
--- a/src/copyin.c
+++ b/src/copyin.c
@@ -124,10 +124,30 @@ tape_skip_padding (int in_file_des, off_t offset)
   if (pad != 0)
     tape_toss_input (in_file_des, pad);
 }
-
+
+static char *
+get_link_name (struct cpio_file_stat *file_hdr, int in_file_des)
+{
+  off_t n = file_hdr->c_filesize + 1;
+  char *link_name;
+  
+  if (n == 0 || n > SIZE_MAX)
+    {
+      error (0, 0, _("%s: stored filename length too big"), file_hdr->c_name);
+      link_name = NULL;
+    }
+  else
+    {
+      link_name = xmalloc (n);
+      tape_buffered_read (link_name, in_file_des, file_hdr->c_filesize);
+      link_name[file_hdr->c_filesize] = '\0';
+      tape_skip_padding (in_file_des, file_hdr->c_filesize);
+    }
+  return link_name;
+}
 
 static void
-list_file(struct cpio_file_stat* file_hdr, int in_file_des)
+list_file (struct cpio_file_stat* file_hdr, int in_file_des)
 {
   if (verbose_flag)
     {
@@ -136,21 +156,16 @@ list_file(struct cpio_file_stat* file_hdr, int in_file_des)
 	{
 	  if (archive_format != arf_tar && archive_format != arf_ustar)
 	    {
-	      char *link_name = NULL;	/* Name of hard and symbolic links.  */
-
-	      link_name = (char *) xmalloc ((unsigned int) file_hdr->c_filesize + 1);
-	      link_name[file_hdr->c_filesize] = '\0';
-	      tape_buffered_read (link_name, in_file_des, file_hdr->c_filesize);
-	      long_format (file_hdr, link_name);
-	      free (link_name);
-	      tape_skip_padding (in_file_des, file_hdr->c_filesize);
-	      return;
+	      char *link_name = get_link_name (file_hdr, in_file_des);
+	      if (link_name)
+		{
+		  long_format (file_hdr, link_name);
+		  free (link_name);
+		}
 	    }
 	  else
-	    {
-	      long_format (file_hdr, file_hdr->c_tar_linkname);
-	      return;
-	    }
+	    long_format (file_hdr, file_hdr->c_tar_linkname);
+	  return;
 	}
       else
 #endif
@@ -650,10 +665,7 @@ copyin_link(struct cpio_file_stat *file_
 
   if (archive_format != arf_tar && archive_format != arf_ustar)
     {
-      link_name = (char *) xmalloc ((unsigned int) file_hdr->c_filesize + 1);
-      link_name[file_hdr->c_filesize] = '\0';
-      tape_buffered_read (link_name, in_file_des, file_hdr->c_filesize);
-      tape_skip_padding (in_file_des, file_hdr->c_filesize);
+      link_name = get_link_name (file_hdr, in_file_des);
     }
   else
     {
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 3f714d1..b4ca92d 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -52,6 +52,8 @@ TESTSUITE_AT = \
  setstat04.at\
  setstat05.at\
  symlink.at\
+ symlink-bad-length.at\
+ symlink-long.at\
  version.at
 
 TESTSUITE = $(srcdir)/testsuite
diff --git a/tests/symlink-bad-length.at b/tests/symlink-bad-length.at
new file mode 100644
index 0000000..6f804b1
--- a/dev/null
+++ b/tests/symlink-bad-length.at
@@ -0,0 +1,49 @@
+# Process this file with autom4te to create testsuite.  -*- Autotest -*-
+# Copyright (C) 2014 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3, or (at your option)
+# any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+# 02110-1301 USA.
+
+# Cpio v2.11 did segfault with badly set symlink length.
+# References:
+# http://lists.gnu.org/archive/html/bug-cpio/2014-11/msg00007.html
+
+AT_SETUP([symlink-bad-length])
+AT_KEYWORDS([symlink-long copyout])
+
+AT_DATA([ARCHIVE.base64],
+[x3EjAIBAtIEtJy8nAQAAAHRUYW0FAAAADQBGSUxFAABzb21lIGNvbnRlbnQKAMdxIwBgQ/+hLScv
+JwEAAAB0VEhuBQD/////TElOSwAARklMRcdxAAAAAAAAAAAAAAEAAAAAAAAACwAAAAAAVFJBSUxF
+UiEhIQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=
+])
+
+AT_CHECK([
+base64 -d ARCHIVE.base64 > ARCHIVE || AT_SKIP_TEST
+cpio -ntv < ARCHIVE
+test $? -eq 2
+],
+[0],
+[-rw-rw-r--   1 10029    10031          13 Nov 25 13:52 FILE
+],[cpio: LINK: stored filename length too big
+cpio: premature end of file
+])
+
+AT_CLEANUP
diff --git a/tests/symlink-long.at b/tests/symlink-long.at
new file mode 100644
index 0000000..d3def2d
--- a/dev/null
+++ b/tests/symlink-long.at
@@ -0,0 +1,46 @@
+# Process this file with autom4te to create testsuite.  -*- Autotest -*-
+# Copyright (C) 2014 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3, or (at your option)
+# any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+# 02110-1301 USA.
+
+# Cpio v2.11.90 changed the way symlink name is read from archive.
+# References:
+# http://lists.gnu.org/archive/html/bug-cpio/2014-11/msg00007.html
+
+AT_SETUP([symlink-long])
+AT_KEYWORDS([symlink-long copyout])
+
+AT_CHECK([
+
+# len(dirname) > READBUFSIZE
+dirname=
+for i in {1..52}; do
+    dirname="xxxxxxxxx/$dirname"
+    mkdir "$dirname"
+done
+ln -s "$dirname" x || AT_SKIP_TEST
+
+echo x | cpio -o > ar
+list=`cpio -tv < ar | sed 's|.*-> ||'`
+test "$list" = "$dirname" && echo success || echo fail
+],
+[0],
+[success
+],[2 blocks
+2 blocks
+])
+
+AT_CLEANUP
diff --git a/tests/testsuite.at b/tests/testsuite.at
index e67689f..3b5377e 100644
--- a/tests/testsuite.at
+++ b/tests/testsuite.at
@@ -31,6 +31,8 @@ m4_include([version.at])
 
 m4_include([inout.at])
 m4_include([symlink.at])
+m4_include([symlink-bad-length.at])
+m4_include([symlink-long.at])
 m4_include([interdir.at])
 
 m4_include([setstat01.at])
--
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