| Andrew Geissler | 9aee500 | 2022-03-30 16:27:02 +0000 | [diff] [blame^] | 1 | From 85c2dd9275cdfb369f613089f22733c0f1ba2aec Mon Sep 17 00:00:00 2001 |
| 2 | From: Jan Rybar <jrybar@redhat.com> |
| 3 | Date: Tue, 25 Jan 2022 17:21:46 +0000 |
| 4 | Subject: [PATCH 1/3] pkexec: local privilege escalation (CVE-2021-4034) |
| 5 | |
| 6 | Signed-off-by: Mikko Rapeli <mikko.rapeli@bmw.de> |
| 7 | |
| 8 | --- |
| 9 | src/programs/pkcheck.c | 5 +++++ |
| 10 | src/programs/pkexec.c | 23 ++++++++++++++++++++--- |
| 11 | 2 files changed, 25 insertions(+), 3 deletions(-) |
| 12 | |
| 13 | CVE: CVE-2021-4034 |
| 14 | Upstream-Status: Backport [a2bf5c9c83b6ae46cbd5c779d3055bff81ded683] |
| 15 | |
| 16 | diff --git a/src/programs/pkcheck.c b/src/programs/pkcheck.c |
| 17 | index f1bb4e1..768525c 100644 |
| 18 | --- a/src/programs/pkcheck.c |
| 19 | +++ b/src/programs/pkcheck.c |
| 20 | @@ -363,6 +363,11 @@ main (int argc, char *argv[]) |
| 21 | local_agent_handle = NULL; |
| 22 | ret = 126; |
| 23 | |
| 24 | + if (argc < 1) |
| 25 | + { |
| 26 | + exit(126); |
| 27 | + } |
| 28 | + |
| 29 | /* Disable remote file access from GIO. */ |
| 30 | setenv ("GIO_USE_VFS", "local", 1); |
| 31 | |
| 32 | diff --git a/src/programs/pkexec.c b/src/programs/pkexec.c |
| 33 | index 7698c5c..84e5ef6 100644 |
| 34 | --- a/src/programs/pkexec.c |
| 35 | +++ b/src/programs/pkexec.c |
| 36 | @@ -488,6 +488,15 @@ main (int argc, char *argv[]) |
| 37 | pid_t pid_of_caller; |
| 38 | gpointer local_agent_handle; |
| 39 | |
| 40 | + |
| 41 | + /* |
| 42 | + * If 'pkexec' is called THIS wrong, someone's probably evil-doing. Don't be nice, just bail out. |
| 43 | + */ |
| 44 | + if (argc<1) |
| 45 | + { |
| 46 | + exit(127); |
| 47 | + } |
| 48 | + |
| 49 | ret = 127; |
| 50 | authority = NULL; |
| 51 | subject = NULL; |
| 52 | @@ -614,10 +623,10 @@ main (int argc, char *argv[]) |
| 53 | |
| 54 | path = g_strdup (pwstruct.pw_shell); |
| 55 | if (!path) |
| 56 | - { |
| 57 | + { |
| 58 | g_printerr ("No shell configured or error retrieving pw_shell\n"); |
| 59 | goto out; |
| 60 | - } |
| 61 | + } |
| 62 | /* If you change this, be sure to change the if (!command_line) |
| 63 | case below too */ |
| 64 | command_line = g_strdup (path); |
| 65 | @@ -636,7 +645,15 @@ main (int argc, char *argv[]) |
| 66 | goto out; |
| 67 | } |
| 68 | g_free (path); |
| 69 | - argv[n] = path = s; |
| 70 | + path = s; |
| 71 | + |
| 72 | + /* argc<2 and pkexec runs just shell, argv is guaranteed to be null-terminated. |
| 73 | + * /-less shell shouldn't happen, but let's be defensive and don't write to null-termination |
| 74 | + */ |
| 75 | + if (argv[n] != NULL) |
| 76 | + { |
| 77 | + argv[n] = path; |
| 78 | + } |
| 79 | } |
| 80 | if (access (path, F_OK) != 0) |
| 81 | { |
| 82 | -- |
| 83 | 2.20.1 |
| 84 | |