patch: fix CVE-2015-1196

A directory traversal flaw was reported in patch:

References:
http://www.openwall.com/lists/oss-security/2015/01/18/6
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=775227
https://bugzilla.redhat.com/show_bug.cgi?id=1182154

[YOCTO #7182]

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 201 insertions, 0 deletions

diff --git a/meta/recipes-devtools/patch/patch/patch-CVE-2015-1196.patch b/meta/recipes-devtools/patch/patch/patch-CVE-2015-1196.patch
new file mode 100644
index 0000000000..d408346ac2
--- /dev/null
+++ b/meta/recipes-devtools/patch/patch/patch-CVE-2015-1196.patch
@@ -0,0 +1,200 @@
+From 4e9269a5fc1fe80a1095a92593dd85db871e1fd3 Mon Sep 17 00:00:00 2001
+From: Andreas Gruenbacher <andreas.gruenbacher@gmail.com>
+Date: Mon, 19 Jan 2015 23:18:30 +0100
+Subject: [PATCH] Make sure symlinks don't point outside working directory
+ (CVE-2015-1196)
+
+When creating symlinks from git-style patches, make sure the symlinks don't
+point above the current working directory.  Otherwise, a subsequent patch could
+use the symlink to write outside the working directory.
+
+* src/pch.c (symlink_target_is_valid): New function to check for valid symlink
+targets.
+* src/util.c (move_file): Use symlink_target_is_valid() here.
+* tests/symlinks: Add valid and invalid symlink test cases.
+
+Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
+
+Upstream-Status: Backport
+
+---
+ NEWS           |  3 ++
+ src/pch.c      | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ src/pch.h      |  1 +
+ src/util.c     |  7 +++++++
+ tests/symlinks | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
+ 5 files changed, 117 insertions(+)
+
+diff --git a/NEWS b/NEWS
+index 42afed7..d3f1c2d 100644
+--- a/NEWS
++++ b/NEWS
+@@ -1,3 +1,6 @@
++* With git-style patches, symlinks that point outside the working directory
++  will no longer be created.
++
+ Changes in version 2.7.1:
+ 
+ * Two critical bug fixes in the "diff --git" format support.
+diff --git a/src/pch.c b/src/pch.c
+index 55e1504..f05ef83 100644
+--- a/src/pch.c
++++ b/src/pch.c
+@@ -454,6 +454,60 @@ name_is_valid (char const *name)
+   return is_valid;
+ }
+ 
++bool
++symlink_target_is_valid (char const *target, char const *to)
++{
++  bool is_valid;
++
++  if (IS_ABSOLUTE_FILE_NAME (to))
++    is_valid = true;
++  else if (IS_ABSOLUTE_FILE_NAME (target))
++    is_valid = false;
++  else
++    {
++      unsigned int depth = 0;
++      char const *t;
++
++      is_valid = true;
++      t = to;
++      while (*t)
++	{
++	  while (*t && ! ISSLASH (*t))
++	    t++;
++	  if (ISSLASH (*t))
++	    {
++	      while (ISSLASH (*t))
++		t++;
++	      depth++;
++	    }
++	}
++
++      t = target;
++      while (*t)
++	{
++	  if (*t == '.' && *++t == '.' && (! *++t || ISSLASH (*t)))
++	    {
++	      if (! depth--)
++		{
++		  is_valid = false;
++		  break;
++		}
++	    }
++	  else
++	    {
++	      while (*t && ! ISSLASH (*t))
++		t++;
++	      depth++;
++	    }
++	  while (ISSLASH (*t))
++	    t++;
++	}
++    }
++
++  /* Allow any symlink target if we are in the filesystem root.  */
++  return is_valid || cwd_is_root (to);
++}
++
+ /* Determine what kind of diff is in the remaining part of the patch file. */
+ 
+ static enum diff
+diff --git a/src/pch.h b/src/pch.h
+index 0c7ff62..58861b0 100644
+--- a/src/pch.h
++++ b/src/pch.h
+@@ -37,6 +37,7 @@ bool pch_write_line (lin, FILE *);
+ bool there_is_another_patch (bool, mode_t *);
+ char *pfetch (lin) _GL_ATTRIBUTE_PURE;
+ char pch_char (lin) _GL_ATTRIBUTE_PURE;
++bool symlink_target_is_valid (char const *, char const *);
+ int another_hunk (enum diff, bool);
+ int pch_says_nonexistent (bool) _GL_ATTRIBUTE_PURE;
+ size_t pch_line_len (lin) _GL_ATTRIBUTE_PURE;
+diff --git a/src/util.c b/src/util.c
+index 66ae90f..636eded 100644
+--- a/src/util.c
++++ b/src/util.c
+@@ -470,6 +470,13 @@ move_file (char const *from, bool *from_needs_removal,
+ 	    read_fatal ();
+ 	  buffer[size] = 0;
+ 
++	  if (! symlink_target_is_valid (buffer, to))
++	    {
++	      fprintf (stderr, "symbolic link target '%s' is invalid\n",
++		       buffer);
++	      fatal_exit (0);
++	    }
++
+ 	  if (! backup)
+ 	    {
+ 	      if (unlink (to) == 0)
+diff --git a/tests/symlinks b/tests/symlinks
+index 96626b3..6211026 100644
+--- a/tests/symlinks
++++ b/tests/symlinks
+@@ -146,6 +146,59 @@ ncheck 'test ! -L symlink'
+ 
+ # --------------------------------------------------------------
+ 
++# Patch should not create symlinks which point outside the working directory.
++
++cat > symlink-target.diff <<EOF
++diff --git a/dir/foo b/dir/foo
++new file mode 120000
++index 0000000..cad2309
++--- /dev/null
+++++ b/dir/foo
++@@ -0,0 +1 @@
+++../foo
++\ No newline at end of file
++EOF
++
++check 'patch -p1 < symlink-target.diff || echo "Status: $?"' <<EOF
++patching symbolic link dir/foo
++EOF
++
++cat > bad-symlink-target1.diff <<EOF
++diff --git a/bar b/bar
++new file mode 120000
++index 0000000..cad2309
++--- /dev/null
+++++ b/bar
++@@ -0,0 +1 @@
+++/bar
++\ No newline at end of file
++EOF
++
++check 'patch -p1 < bad-symlink-target1.diff || echo "Status: $?"' <<EOF
++patching symbolic link bar
++symbolic link target '/bar' is invalid
++Status: 2
++EOF
++
++cat > bad-symlink-target2.diff <<EOF
++diff --git a/baz b/baz
++new file mode 120000
++index 0000000..cad2309
++--- /dev/null
+++++ b/baz
++@@ -0,0 +1 @@
+++../baz
++\ No newline at end of file
++EOF
++
++check 'patch -p1 < bad-symlink-target2.diff || echo "Status: $?"' <<EOF
++patching symbolic link baz
++symbolic link target '../baz' is invalid
++Status: 2
++EOF
++
++# --------------------------------------------------------------
++
+ # The backup file of a new symlink is an empty regular file.
+ 
+ check 'patch -p1 --backup < create-symlink.diff || echo "Status: $?"' <<EOF
+-- 
+2.1.4
+
diff --git a/meta/recipes-devtools/patch/patch_2.7.1.bb b/meta/recipes-devtools/patch/patch_2.7.1.bb
index 3db318a7ec..1a3b9b1201 100644
--- a/meta/recipes-devtools/patch/patch_2.7.1.bb
+++ b/meta/recipes-devtools/patch/patch_2.7.1.bb
@@ -1,6 +1,7 @@
 require patch.inc
 LICENSE = "GPLv3"
 
+SRC_URI += "file://patch-CVE-2015-1196.patch"
 
 SRC_URI[md5sum] = "95dd8d7e41dcbcecdd5cd88ef915378d"
 SRC_URI[sha256sum] = "c05f28668c3474bc63adcd48abae921d15e71c254fbebdbaeda40456d64039d5"