| From 85c2dd9275cdfb369f613089f22733c0f1ba2aec Mon Sep 17 00:00:00 2001 |
| From: Jan Rybar <jrybar@redhat.com> |
| Date: Tue, 25 Jan 2022 17:21:46 +0000 |
| Subject: [PATCH 1/3] pkexec: local privilege escalation (CVE-2021-4034) |
| |
| Signed-off-by: Mikko Rapeli <mikko.rapeli@bmw.de> |
| |
| --- |
| src/programs/pkcheck.c | 5 +++++ |
| src/programs/pkexec.c | 23 ++++++++++++++++++++--- |
| 2 files changed, 25 insertions(+), 3 deletions(-) |
| |
| CVE: CVE-2021-4034 |
| Upstream-Status: Backport [a2bf5c9c83b6ae46cbd5c779d3055bff81ded683] |
| |
| 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) |
| { |
| -- |
| 2.20.1 |
| |