pkexec: argv overflow results in local privilege esc.

CVE-2021-4034.patch

@@ -0,0 +1,72 @@
+commit a2bf5c9c83b6ae46cbd5c779d3055bff81ded683
+Author: Jan Rybar <jrybar@redhat.com>
+Date:   Tue Jan 25 17:21:46 2022 +0000
+
+    pkexec: local privilege escalation (CVE-2021-4034)
+
+diff --git a/src/programs/pkcheck.c b/src/programs/pkcheck.c
+index f1bb4e1..768525c 100644
+--- a/src/programs/pkcheck.c
++++ b/src/programs/pkcheck.c
+@@ -363,6 +363,11 @@ main (int argc, char *argv[])
+   local_agent_handle = NULL;
+   ret = 126;
+ 
++  if (argc < 1)
++    {
++      exit(126);
++    }
++
+   /* 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..84e5ef6 100644
+--- a/src/programs/pkexec.c
++++ b/src/programs/pkexec.c
+@@ -488,6 +488,15 @@ main (int argc, char *argv[])
+   pid_t pid_of_caller;
+   gpointer local_agent_handle;
+ 
++
++  /*
++   * If 'pkexec' is called THIS wrong, someone's probably evil-doing. Don't be nice, just bail out.
++   */
++  if (argc<1)
++    {
++      exit(127);
++    }
++
+   ret = 127;
+   authority = NULL;
+   subject = NULL;
+@@ -614,10 +623,10 @@ main (int argc, char *argv[])
+ 
+       path = g_strdup (pwstruct.pw_shell);
+       if (!path)
+-	{
++        {
+           g_printerr ("No shell configured or error retrieving pw_shell\n");
+           goto out;
+-	}
++        }
+       /* If you change this, be sure to change the if (!command_line)
+ 	 case below too */
+       command_line = g_strdup (path);
+@@ -636,7 +645,15 @@ 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)
+     {

polkit.spec

@@ -22,7 +22,7 @@
 Summary: An authorization framework
 Name: polkit
 Version: 0.117
-Release: 7%{?dist}
+Release: 8%{?dist}
 License: LGPLv2+
 URL: http://www.freedesktop.org/wiki/Software/polkit
 Source0: http://www.freedesktop.org/software/polkit/releases/%{name}-%{version}.tar.gz
@@ -30,6 +30,7 @@ Source1: http://www.freedesktop.org/software/polkit/releases/%{name}-%{version}.
 
 Patch1001: mozjs78.patch
 Patch1002: CVE-2021-3560.patch
+Patch1003: CVE-2021-4034.patch
 
 %if 0%{?bundled_mozjs}
 Source2: https://ftp.mozilla.org/pub/firefox/releases/%{mozjs_version}esr/source/firefox-%{mozjs_version}esr.source.tar.xz
@@ -175,6 +176,7 @@ Libraries files for polkit.
 # Apply polkit patches
 %patch1001 -p1
 %patch1002 -p1
+%patch1003 -p1
 
 %if 0%{?bundled_mozjs}
 # Extract mozjs archive
@@ -381,6 +383,10 @@ exit 0
 %endif
 
 %changelog
+* Thu Jan 27 2022 Jan Rybar <jrybar@redhat.com> - 0.117-8
+- pkexec: argv overflow results in local privilege esc.
+- Resolves: CVE-2021-4034
+
 * Tue Aug 10 2021 Mohan Boddu <mboddu@redhat.com> - 0.117-7
 - Rebuilt for IMA sigs, glibc 2.34, aarch64 flags
   Related: rhbz#1991688