Submitted By: Xi Ruoyao Date: 2021-01-27 Initial Package Version: 0.113 Upstream Status: Applied Origin: Upstream, rebased for polkit <= 0.113, >= 0.92 Description: Fix CVE-2021-4034, a trivially exploitable local privilege escalation, to polkit since 0.92. From 034272c322534ab2b665c23c40380723ef15f0a9 Mon Sep 17 00:00:00 2001 From: Jan Rybar Date: Tue, 25 Jan 2022 17:21:46 +0000 Subject: [PATCH] pkexec: local privilege escalation (CVE-2021-4034) --- src/programs/pkcheck.c | 5 +++++ src/programs/pkexec.c | 19 ++++++++++++++++++- 2 files changed, 23 insertions(+), 1 deletion(-) diff --git a/src/programs/pkcheck.c b/src/programs/pkcheck.c index 5781893..63c0559 100644 --- a/src/programs/pkcheck.c +++ b/src/programs/pkcheck.c @@ -362,6 +362,11 @@ main (int argc, char *argv[]) local_agent_handle = NULL; ret = 126; + if (argc < 1) + { + exit(126); + } + g_type_init (); details = polkit_details_new (); diff --git a/src/programs/pkexec.c b/src/programs/pkexec.c index 50de92c..c31356f 100644 --- a/src/programs/pkexec.c +++ b/src/programs/pkexec.c @@ -490,6 +490,15 @@ 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; @@ -635,7 +644,15 @@ 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) { -- 2.35.0