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-rw-r--r--gnu/packages/patches/shadow-CVE-2017-2616.patch72
1 files changed, 72 insertions, 0 deletions
diff --git a/gnu/packages/patches/shadow-CVE-2017-2616.patch b/gnu/packages/patches/shadow-CVE-2017-2616.patch
new file mode 100644
index 0000000000..f88aac40bc
--- /dev/null
+++ b/gnu/packages/patches/shadow-CVE-2017-2616.patch
@@ -0,0 +1,72 @@
+Fix CVE-2017-2616:
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-2616
+http://seclists.org/oss-sec/2017/q1/490
+http://seclists.org/oss-sec/2017/q1/474
+
+Patch copied from upstream source repository:
+
+https://github.com/shadow-maint/shadow/commit/08fd4b69e84364677a10e519ccb25b71710ee686
+
+From 08fd4b69e84364677a10e519ccb25b71710ee686 Mon Sep 17 00:00:00 2001
+From: Tobias Stoeckmann <tobias@stoeckmann.org>
+Date: Thu, 23 Feb 2017 09:47:29 -0600
+Subject: [PATCH] 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.
+---
+ src/su.c | 19 +++++++++++++++++--
+ 1 file changed, 17 insertions(+), 2 deletions(-)
+
+diff --git a/src/su.c b/src/su.c
+index f20d230..d86aa86 100644
+--- a/src/su.c
++++ b/src/su.c
+@@ -379,11 +379,13 @@ 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);
+@@ -393,9 +395,22 @@ static void prepare_pam_close_session (void)
+ snprintf (wait_msg, sizeof wait_msg, _(" ...waiting for child to terminate.\n"));
+
+ (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);
+ }
+