From b71d112385937fdffac8bb78df279b23bc9441c4 Mon Sep 17 00:00:00 2001

From: Jan Synacek <jsynacek@redhat.com>

Date: Tue, 4 Dec 2018 10:01:35 +0100

Subject: [PATCH] core: enforce a limit on STATUS= texts recvd from services

Let's better be safe than sorry, and put a limit on what we receive.

(cherry picked from commit 3eac1bcae9284fb8b18f4b82156c0e85ddb004e5)

Related: CVE-2018-15686

---

 src/core/service.c | 8 ++++++--

 src/core/service.h | 2 ++

 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/core/service.c b/src/core/service.c

index 4d542ad947..fe6e2ff17c 100644

--- a/src/core/service.c

+++ b/src/core/service.c

@@ -3045,8 +3045,12 @@ static void service_notify_message(Unit *u, pid_t pid, char **tags, FDSet *fds)

                 _cleanup_free_ char *t = NULL;

                 if (!isempty(e)) {

-                        if (!utf8_is_valid(e))

-                                log_unit_warning(u->id, "Status message in notification is not UTF-8 clean.");

+                        /* Note that this size limit check is mostly paranoia: since the datagram size we are willing

+                         * to process is already limited to NOTIFY_BUFFER_MAX, this limit here should never be hit. */

+                        if (strlen(e) > STATUS_TEXT_MAX)

+                                log_unit_warning(u->id, "Status message overly long (%zu > %u), ignoring.", strlen(e), STATUS_TEXT_MAX);

+                        else if (!utf8_is_valid(e))

+                                log_unit_warning(u->id, "Status message in notification message is not UTF-8 clean, ignoring.");

                         else {

                                 log_unit_debug(u->id, "%s: got STATUS=%s", u->id, e);

diff --git a/src/core/service.h b/src/core/service.h

index 1f937dfe57..e0547a464e 100644

--- a/src/core/service.h

+++ b/src/core/service.h

@@ -31,6 +31,8 @@ typedef struct ServiceFDStore ServiceFDStore;

 #include "exit-status.h"

 #include "emergency-action.h"

+#define STATUS_TEXT_MAX (16U*1024U)

+

 typedef enum ServiceState {

         SERVICE_DEAD,

         SERVICE_START_PRE,