daandemeyer / rpms / systemd

Forked from rpms/systemd 2 years ago
Clone
4fbe94
From 980418c331293aeb8595fcc95cbc4a9e1a485eda Mon Sep 17 00:00:00 2001
4fbe94
From: Lennart Poettering <lennart@poettering.net>
4fbe94
Date: Mon, 25 Feb 2019 11:02:46 +0100
4fbe94
Subject: [PATCH] sd-bus: deal with cookie overruns
4fbe94
4fbe94
Apparently this happens IRL. Let's carefully deal with issues like this:
4fbe94
when we overrun, let's not go back to zero but instead leave the highest
4fbe94
cookie bit set. We use that as indication that we are in "overrun
4fbe94
territory", and then are particularly careful with checking cookies,
4fbe94
i.e. that they haven't been used for still outstanding replies yet. This
4fbe94
should retain the quick cookie generation behaviour we used to have, but
4fbe94
permits dealing with overruns.
4fbe94
4fbe94
Replaces: #11804
4fbe94
Fixes: #11809
4fbe94
(cherry picked from commit 1f82f5bb4237ed5f015daf93f818e9db95e764b8)
4fbe94
4fbe94
Resolves: #1694999
4fbe94
---
4fbe94
 src/libsystemd/sd-bus/sd-bus.c | 47 +++++++++++++++++++++++++++++++++-
4fbe94
 1 file changed, 46 insertions(+), 1 deletion(-)
4fbe94
4fbe94
diff --git a/src/libsystemd/sd-bus/sd-bus.c b/src/libsystemd/sd-bus/sd-bus.c
4fbe94
index f53a98d6bf..3583e24e64 100644
4fbe94
--- a/src/libsystemd/sd-bus/sd-bus.c
4fbe94
+++ b/src/libsystemd/sd-bus/sd-bus.c
4fbe94
@@ -1597,6 +1597,47 @@ _public_ int sd_bus_get_bus_id(sd_bus *bus, sd_id128_t *id) {
4fbe94
         return 0;
4fbe94
 }
4fbe94
 
4fbe94
+#define COOKIE_CYCLED (UINT32_C(1) << 31)
4fbe94
+
4fbe94
+static uint64_t cookie_inc(uint64_t cookie) {
4fbe94
+
4fbe94
+        /* Stay within the 32bit range, since classic D-Bus can't deal with more */
4fbe94
+        if (cookie >= UINT32_MAX)
4fbe94
+                return COOKIE_CYCLED; /* Don't go back to zero, but use the highest bit for checking
4fbe94
+                                       * whether we are looping. */
4fbe94
+
4fbe94
+        return cookie + 1;
4fbe94
+}
4fbe94
+
4fbe94
+static int next_cookie(sd_bus *b) {
4fbe94
+        uint64_t new_cookie;
4fbe94
+
4fbe94
+        assert(b);
4fbe94
+
4fbe94
+        new_cookie = cookie_inc(b->cookie);
4fbe94
+
4fbe94
+        /* Small optimization: don't bother with checking for cookie reuse until we overran cookiespace at
4fbe94
+         * least once, but then do it thorougly. */
4fbe94
+        if (FLAGS_SET(new_cookie, COOKIE_CYCLED)) {
4fbe94
+                uint32_t i;
4fbe94
+
4fbe94
+                /* Check if the cookie is currently in use. If so, pick the next one */
4fbe94
+                for (i = 0; i < COOKIE_CYCLED; i++) {
4fbe94
+                        if (!ordered_hashmap_contains(b->reply_callbacks, &new_cookie))
4fbe94
+                                goto good;
4fbe94
+
4fbe94
+                        new_cookie = cookie_inc(new_cookie);
4fbe94
+                }
4fbe94
+
4fbe94
+                /* Can't fulfill request */
4fbe94
+                return -EBUSY;
4fbe94
+        }
4fbe94
+
4fbe94
+good:
4fbe94
+        b->cookie = new_cookie;
4fbe94
+        return 0;
4fbe94
+}
4fbe94
+
4fbe94
 static int bus_seal_message(sd_bus *b, sd_bus_message *m, usec_t timeout) {
4fbe94
         int r;
4fbe94
 
4fbe94
@@ -1620,7 +1661,11 @@ static int bus_seal_message(sd_bus *b, sd_bus_message *m, usec_t timeout) {
4fbe94
                         return r;
4fbe94
         }
4fbe94
 
4fbe94
-        return sd_bus_message_seal(m, ++b->cookie, timeout);
4fbe94
+        r = next_cookie(b);
4fbe94
+        if (r < 0)
4fbe94
+                return r;
4fbe94
+
4fbe94
+        return sd_bus_message_seal(m, b->cookie, timeout);
4fbe94
 }
4fbe94
 
4fbe94
 static int bus_remarshal_message(sd_bus *b, sd_bus_message **m) {