CVE-2021-4034: polkit Local privilege escalation in pkexec due to incorrect handling of argument vector

Upstream-Status: Backport
CVE: CVE-2021-4034

Signed-off-by: Jeremy A. Puhlman <jpuhlman@mvista.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>

2 files changed, 75 insertions, 0 deletions

diff --git a/meta-oe/recipes-extended/polkit/files/CVE-2021-4034.patch b/meta-oe/recipes-extended/polkit/files/CVE-2021-4034.patch
new file mode 100644
index 0000000000..cab1c83c09
--- /dev/null
+++ b/meta-oe/recipes-extended/polkit/files/CVE-2021-4034.patch
@@ -0,0 +1,74 @@
+From ed8b418f1341cf7fc576f6b17de5c6dd4017e034 Mon Sep 17 00:00:00 2001
+From: "Jeremy A. Puhlman" <jpuhlman@mvista.com>
+Date: Thu, 27 Jan 2022 00:01:27 +0000
+Subject: [PATCH] CVE-2021-4034: Local privilege escalation in pkexec due to 
+ incorrect handling of argument vector
+
+Upstream-Status: Backport https://gitlab.freedesktop.org/polkit/polkit/-/commit/a2bf5c9c83b6ae46cbd5c779d3055bff81ded683
+CVE: CVE-2021-4034
+
+Signed-off-by: Jeremy A. Puhlman <jpuhlman@mvista.com>
+---
+ src/programs/pkcheck.c |  6 ++++++
+ src/programs/pkexec.c  | 21 ++++++++++++++++++++-
+ 2 files changed, 26 insertions(+), 1 deletion(-)
+
+diff --git a/src/programs/pkcheck.c b/src/programs/pkcheck.c
+index f1bb4e1..aff4f60 100644
+--- a/src/programs/pkcheck.c
++++ b/src/programs/pkcheck.c
+@@ -363,6 +363,12 @@ main (int argc, char *argv[])
+   local_agent_handle = NULL;
+   ret = 126;
+ 
++  if (argc < 1)
++    {
++      help();
++      exit(1);
++    }
++
+   /* Disable remote file access from GIO. */
+   setenv ("GIO_USE_VFS", "local", 1);
+ 
+diff --git a/src/programs/pkexec.c b/src/programs/pkexec.c
+index 7698c5c..3ff4c58 100644
+--- a/src/programs/pkexec.c
++++ b/src/programs/pkexec.c
+@@ -488,6 +488,17 @@ main (int argc, char *argv[])
+   pid_t pid_of_caller;
+   gpointer local_agent_handle;
+ 
++
++  /*
++   * If 'pkexec' is called wrong, just show help and bail out.
++   */
++  if (argc<1)
++    {
++      clearenv();
++      usage(argc, argv);
++      exit(1);
++    }
++
+   ret = 127;
+   authority = NULL;
+   subject = NULL;
+@@ -636,7 +647,15 @@ main (int argc, char *argv[])
+           goto out;
+         }
+       g_free (path);
+-      argv[n] = path = s;
++      path = s;
++
++      /* argc<2 and pkexec runs just shell, argv is guaranteed to be null-terminated.
++       * /-less shell shouldn't happen, but let's be defensive and don't write to null-termination
++       */
++      if (argv[n] != NULL)
++      {
++        argv[n] = path;
++      }
+     }
+   if (access (path, F_OK) != 0)
+     {
+-- 
+2.26.2
+
diff --git a/meta-oe/recipes-extended/polkit/polkit_0.116.bb b/meta-oe/recipes-extended/polkit/polkit_0.116.bb
index ad1973b136..77288b0082 100644
--- a/meta-oe/recipes-extended/polkit/polkit_0.116.bb
+++ b/meta-oe/recipes-extended/polkit/polkit_0.116.bb
@@ -25,6 +25,7 @@ PAM_SRC_URI = "file://polkit-1_pam.patch"
 SRC_URI = "http://www.freedesktop.org/software/polkit/releases/polkit-${PV}.tar.gz \
            ${@bb.utils.contains('DISTRO_FEATURES', 'pam', '${PAM_SRC_URI}', '', d)} \
            file://0003-make-netgroup-support-optional.patch \
+           file://CVE-2021-4034.patch \
            "
 SRC_URI[md5sum] = "4b37258583393e83069a0e2e89c0162a"
 SRC_URI[sha256sum] = "88170c9e711e8db305a12fdb8234fac5706c61969b94e084d0f117d8ec5d34b1"