# HG changeset patch
# User Todd C. Miller <Todd.Miller@sudo.ws>
# Date 1544201494 25200
# Node ID 656aa910fbaf0be517e012c9271c51eb85c1cca5
# Parent  ef83f35c9cb090a8b4fd36942f1e47e65c285dce
The fix for bug #843 was incomplete and caused pam_end() to be called early.
sudo_pam_approval() must not set the global pam status to an error
value if it returns AUTH_SUCCESS.  Otherwise, sudo_pam_cleanup()
will call pam_end() before sudo_pam_begin_session().  This resulted
in a NULL PAM handle being used in sudo_pam_begin_session().

diff -r ef83f35c9cb0 -r 656aa910fbaf plugins/sudoers/auth/pam.c
--- a/plugins/sudoers/auth/pam.c	Wed Dec 05 10:43:14 2018 -0700
+++ b/plugins/sudoers/auth/pam.c	Fri Dec 07 09:51:34 2018 -0700
@@ -210,59 +210,68 @@
 sudo_pam_approval(struct passwd *pw, sudo_auth *auth, bool exempt)
 {
     const char *s;
+    int rc, status = AUTH_SUCCESS;
     int *pam_status = (int *) auth->data;
     debug_decl(sudo_pam_approval, SUDOERS_DEBUG_AUTH)
 
-    *pam_status = pam_acct_mgmt(pamh, PAM_SILENT);
-    switch (*pam_status) {
+    rc = pam_acct_mgmt(pamh, PAM_SILENT);
+    switch (rc) {
 	case PAM_SUCCESS:
-	    debug_return_int(AUTH_SUCCESS);
+	    break;
 	case PAM_AUTH_ERR:
 	    log_warningx(0, N_("account validation failure, "
 		"is your account locked?"));
-	    debug_return_int(AUTH_FATAL);
+	    status = AUTH_FATAL;
+	    break;
 	case PAM_NEW_AUTHTOK_REQD:
 	    /* Ignore if user is exempt from password restrictions. */
 	    if (exempt)
-		debug_return_int(AUTH_SUCCESS);
+		break;
 	    /* New password required, try to change it. */
 	    log_warningx(0, N_("Account or password is "
 		"expired, reset your password and try again"));
-	    *pam_status = pam_chauthtok(pamh,
-		PAM_CHANGE_EXPIRED_AUTHTOK);
-	    if (*pam_status == PAM_SUCCESS)
-		debug_return_int(AUTH_SUCCESS);
-	    if ((s = pam_strerror(pamh, *pam_status)) == NULL)
+	    rc = pam_chauthtok(pamh, PAM_CHANGE_EXPIRED_AUTHTOK);
+	    if (rc == PAM_SUCCESS)
+		break;
+	    if ((s = pam_strerror(pamh, rc)) == NULL)
 		s = "unknown error";
 	    log_warningx(0,
 		N_("unable to change expired password: %s"), s);
-	    debug_return_int(AUTH_FAILURE);
+	    status = AUTH_FAILURE;
+	    break;
 	case PAM_AUTHTOK_EXPIRED:
 	    /* Ignore if user is exempt from password restrictions. */
 	    if (exempt)
-		debug_return_int(AUTH_SUCCESS);
+		break;
 	    /* Password expired, cannot be updated by user. */
 	    log_warningx(0,
 		N_("Password expired, contact your system administrator"));
-	    debug_return_int(AUTH_FATAL);
+	    status = AUTH_FATAL;
+	    break;
 	case PAM_ACCT_EXPIRED:
 	    log_warningx(0,
 		N_("Account expired or PAM config lacks an \"account\" "
 		"section for sudo, contact your system administrator"));
-	    debug_return_int(AUTH_FATAL);
+	    status = AUTH_FATAL;
+	    break;
 	case PAM_AUTHINFO_UNAVAIL:
 	case PAM_MAXTRIES:
 	case PAM_PERM_DENIED:
-	    s = pam_strerror(pamh, *pam_status);
+	    s = pam_strerror(pamh, rc);
 	    log_warningx(0, N_("PAM account management error: %s"),
 		s ? s : "unknown error");
-	    debug_return_int(AUTH_FAILURE);
+	    status = AUTH_FAILURE;
+	    break;
 	default:
-	    s = pam_strerror(pamh, *pam_status);
+	    s = pam_strerror(pamh, rc);
 	    log_warningx(0, N_("PAM account management error: %s"),
 		s ? s : "unknown error");
-	    debug_return_int(AUTH_FATAL);
+	    status = AUTH_FATAL;
+	    break;
     }
+    /* Ignore errors if user is exempt from password restrictions. */
+    *pam_status = exempt ? PAM_SUCCESS : rc;
+    debug_return_int(status);
 }
 
 int