[oe-commits] [openembedded-core] 47/58: shadow: fix CVE-2017-2616
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git at git.openembedded.org
Wed Jul 25 21:46:17 UTC 2018
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rpurdie pushed a commit to branch master-next
in repository openembedded-core.
commit 5da3f7bbcb2307915c0807cd3b83b40736f6e82b
Author: Andrej Valek <andrej.valek at siemens.com>
AuthorDate: Tue Jul 24 13:08:29 2018 +0200
shadow: fix CVE-2017-2616
Signed-off-by: Andrej Valek <andrej.valek at siemens.com>
Signed-off-by: Ross Burton <ross.burton at intel.com>
---
.../shadow/files/CVE-2017-2616.patch | 64 ++++++++++++++++++++++
meta/recipes-extended/shadow/shadow.inc | 1 +
2 files changed, 65 insertions(+)
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 0000000..ee728f0
--- /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 $(whoami)". Second, SIGKILL
+can only be sent to processes which were executed after the su process.
+It is not possible to send SIGKILL to processes which were already
+running. I consider this as a security vulnerability, because I was
+able to write a proof of concept which unlocked a screen saver of
+another user this way.
+
+Upstream-Status: Backport [https://github.com/shadow-maint/shadow/commit/08fd4b69e84364677a10e519ccb25b71710ee686]
+CVE: CVE-2017-2616
+bug: 855943
+Signed-off-by: Andrej Valek <andrej.valek at siemens.com>
+
+diff --git a/src/su.c b/src/su.c
+index 3704217..1efcd61 100644
+--- a/src/su.c
++++ b/src/su.c
+@@ -363,20 +363,35 @@ static void prepare_pam_close_session (void)
+ /* wake child when resumed */
+ kill (pid, SIGCONT);
+ stop = false;
++ } else {
++ pid_child = 0;
+ }
+ } while (!stop);
+ }
+
+- if (0 != caught) {
++ if (0 != caught && 0 != pid_child) {
+ (void) fputs ("\n", stderr);
+ (void) fputs (_("Session terminated, terminating shell..."),
+ stderr);
+ (void) kill (-pid_child, caught);
+
+ (void) signal (SIGALRM, kill_child);
++ (void) signal (SIGCHLD, catch_signals);
+ (void) alarm (2);
+
+- (void) wait (&status);
++ sigemptyset (&ourset);
++ if ((sigaddset (&ourset, SIGALRM) != 0)
++ || (sigprocmask (SIG_BLOCK, &ourset, NULL) != 0)) {
++ fprintf (stderr, _("%s: signal masking malfunction\n"), Prog);
++ kill_child (0);
++ } else {
++ while (0 == waitpid (pid_child, &status, WNOHANG)) {
++ sigsuspend (&ourset);
++ }
++ pid_child = 0;
++ (void) sigprocmask (SIG_UNBLOCK, &ourset, NULL);
++ }
++
+ (void) fputs (_(" ...terminated.\n"), stderr);
+ }
+
diff --git a/meta/recipes-extended/shadow/shadow.inc b/meta/recipes-extended/shadow/shadow.inc
index 9a08918..6efe4a9 100644
--- a/meta/recipes-extended/shadow/shadow.inc
+++ b/meta/recipes-extended/shadow/shadow.inc
@@ -18,6 +18,7 @@ SRC_URI = "https://downloads.yoctoproject.org/mirror/sources/${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)} \
"
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