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authorAndrej Valek <andrej.valek@siemens.com>2018-07-24 13:08:29 +0200
committerRichard Purdie <richard.purdie@linuxfoundation.org>2018-10-10 13:26:53 +0100
commiteec9169658733335c6f8251b5122706fa8ab467d (patch)
treead032d56886b586b272ca698e9a67746698f3ab9
parent9aed83eb8694a0bd409a6a2481bfd2a1b98919e1 (diff)
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shadow: fix CVE-2017-2616
(From OE-Core rev: 94a1e2794df15f0f2cb62ae030cd81e6c0798b1f) (From OE-Core rev: 8894c70ae5a44974f74434d251def3148818a866) Signed-off-by: Andrej Valek <andrej.valek@siemens.com> Signed-off-by: Ross Burton <ross.burton@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org> Signed-off-by: Armin Kuster <akuster808@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org> Signed-off-by: Armin Kuster <akuster808@gmail.com>
-rw-r--r--meta/recipes-extended/shadow/files/CVE-2017-2616.patch64
-rw-r--r--meta/recipes-extended/shadow/shadow.inc1
2 files changed, 65 insertions, 0 deletions
diff --git a/meta/recipes-extended/shadow/files/CVE-2017-2616.patch b/meta/recipes-extended/shadow/files/CVE-2017-2616.patch
new file mode 100644
index 0000000000..ee728f0952
--- /dev/null
+++ b/meta/recipes-extended/shadow/files/CVE-2017-2616.patch
@@ -0,0 +1,64 @@
+shadow-4.2.1: Fix CVE-2017-2616
+
+[No upstream tracking] -- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=855943
+
+su: properly clear child PID
+
+If su is compiled with PAM support, it is possible for any local user
+to send SIGKILL to other processes with root privileges. There are
+only two conditions. First, the user must be able to perform su with
+a successful login. This does NOT have to be the root user, even using
+su with the same id is enough, e.g. "su $(whoami)". Second, SIGKILL
+can only be sent to processes which were executed after the su process.
+It is not possible to send SIGKILL to processes which were already
+running. I consider this as a security vulnerability, because I was
+able to write a proof of concept which unlocked a screen saver of
+another user this way.
+
+Upstream-Status: Backport [https://github.com/shadow-maint/shadow/commit/08fd4b69e84364677a10e519ccb25b71710ee686]
+CVE: CVE-2017-2616
+bug: 855943
+Signed-off-by: Andrej Valek <andrej.valek@siemens.com>
+
+diff --git a/src/su.c b/src/su.c
+index 3704217..1efcd61 100644
+--- a/src/su.c
++++ b/src/su.c
+@@ -363,20 +363,35 @@ static void prepare_pam_close_session (void)
+ /* wake child when resumed */
+ kill (pid, SIGCONT);
+ stop = false;
++ } else {
++ pid_child = 0;
+ }
+ } while (!stop);
+ }
+
+- if (0 != caught) {
++ if (0 != caught && 0 != pid_child) {
+ (void) fputs ("\n", stderr);
+ (void) fputs (_("Session terminated, terminating shell..."),
+ stderr);
+ (void) kill (-pid_child, caught);
+
+ (void) signal (SIGALRM, kill_child);
++ (void) signal (SIGCHLD, catch_signals);
+ (void) alarm (2);
+
+- (void) wait (&status);
++ sigemptyset (&ourset);
++ if ((sigaddset (&ourset, SIGALRM) != 0)
++ || (sigprocmask (SIG_BLOCK, &ourset, NULL) != 0)) {
++ fprintf (stderr, _("%s: signal masking malfunction\n"), Prog);
++ kill_child (0);
++ } else {
++ while (0 == waitpid (pid_child, &status, WNOHANG)) {
++ sigsuspend (&ourset);
++ }
++ pid_child = 0;
++ (void) sigprocmask (SIG_UNBLOCK, &ourset, NULL);
++ }
++
+ (void) fputs (_(" ...terminated.\n"), stderr);
+ }
+
diff --git a/meta/recipes-extended/shadow/shadow.inc b/meta/recipes-extended/shadow/shadow.inc
index ccae09183c..5a493856a3 100644
--- a/meta/recipes-extended/shadow/shadow.inc
+++ b/meta/recipes-extended/shadow/shadow.inc
@@ -19,6 +19,7 @@ SRC_URI = "https://downloads.yoctoproject.org/mirror/sources/${BP}.tar.xz \
file://check_size_of_uid_t_and_gid_t_using_AC_CHECK_SIZEOF.patch \
file://0001-useradd-copy-extended-attributes-of-home.patch \
file://0001-shadow-CVE-2017-12424 \
+ file://CVE-2017-2616.patch \
${@bb.utils.contains('PACKAGECONFIG', 'pam', '${PAM_SRC_URI}', '', d)} \
"