[PATCH v3 1/1] rpc: avoid crash when system time jump back

[BiaoxiangYe <yebiaoxiang@xxxxxxxxxx>]

From: BiaoXiang Ye <yebiaoxiang@xxxxxxxxxx>

 Setting the system time backward would lead to a
 multiplication overflow in function virKeepAliveStart.
 The function virKeepAliveTimerInternal got the same bug too.

 Backtrace below:
 #0  0x0000ffffae898470 in raise () from /usr/lib64/libc.so.6
 #1  0x0000ffffae89981c in abort () from /usr/lib64/libc.so.6
 #2  0x0000ffffaf9a36a8 in __mulvsi3 () from /usr/lib64/libvirt.so.0
 #3  0x0000ffffaf8fd9e8 in virKeepAliveStart (ka=0xaaaaf954ce10, interval=interval entry=0,
     count=count entry=0) at ../../src/rpc/virkeepalive.c:283
 #4  0x0000ffffaf908560 in virNetServerClientStartKeepAlive (client=0xaaaaf954cbe0)
     at ../../src/rpc/virnetserverclient.c:1628
 #5  0x0000aaaac57eb6dc in remoteDispatchConnectSupportsFeature (server=0xaaaaf95309d0,
     msg=0xaaaaf9549d90, ret=0xffff8c007fc0, args=0xffff8c002e70, rerr=0xffff9ea054a0,
     client=0xaaaaf954cbe0) at ../../src/remote/remote_daemon_dispatch.c:5063
 #6  remoteDispatchConnectSupportsFeatureHelper (server=0xaaaaf95309d0, client=0xaaaaf954cbe0,
     msg=0xaaaaf9549d90, rerr=0xffff9ea054a0, args=0xffff8c002e70, ret=0xffff8c007fc0)
     at ./remote/remote_daemon_dispatch_stubs.h:3503
 #7  0x0000ffffaf9053a4 in virNetServerProgramDispatchCall(msg=0xaaaaf9549d90, client=0xaaaaf954cbe0,
     server=0x0, prog=0xaaaaf953a170) at ../../src/rpc/virnetserverprogram.c:451
 #8  virNetServerProgramDispatch (prog=0xaaaaf953a170, server=0x0, server entry=0xaaaaf95309d0,
     client=0xaaaaf954cbe0, msg=0xaaaaf9549d90) at ../../src/rpc/virnetserverprogram.c:306
 #9  0x0000ffffaf90a6bc in virNetServerProcessMsg (msg=<optimized out>, prog=<optimized out>,
     client=<optimized out>, srv=0xaaaaf95309d0) at ../../src/rpc/virnetserver.c:137
 #10 virNetServerHandleJob (jobOpaque=0xaaaaf950df80, opaque=0xaaaaf95309d0)
     at ../../src/rpc/virnetserver.c:154
 #11 0x0000ffffaf812e14 in virThreadPoolWorker (opaque=<optimized out>)
     at ../../src/util/virthreadpool.c:163
 #12 0x0000ffffaf81237c in virThreadHelper (data=<optimized out>) at ../../src/util/virthread.c:246
 #13 0x0000ffffaea327ac in ?? () from /usr/lib64/libpthread.so.0
 #14 0x0000ffffae93747c in ?? () from /usr/lib64/libc.so.6
 (gdb) frame 3
 #3  0x0000ffffaf8fd9e8 in virKeepAliveStart (ka=0xaaaaf954ce10, interval=interval entry=0,
     count=count entry=0) at ../../src/rpc/virkeepalive.c:283
 283            timeout = ka->interval - delay;
 (gdb) list
 278    now = time(NULL);
 279    delay = now - ka->lastPacketReceived; <='delay' got a negative value
 280    if (delay > ka->interval)
 281        timeout = 0;
 282    else
 283        timeout = ka->interval - delay;
 284    ka->intervalStart = now - (ka->interval - timeout);
 285    ka->timer = virEventAddTimeout(timeout * 1000, virKeepAliveTimer, <= multiplication overflow
 286                                   ka, virObjectFreeCallback);
 287    if (ka->timer < 0)
 (gdb) p now
 $2 = 18288001
 (gdb) p ka->lastPacketReceived
 $3 = 1609430405

Signed-off-by: BiaoXiang Ye <yebiaoxiang@xxxxxxxxxx>
---
 src/rpc/virkeepalive.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/src/rpc/virkeepalive.c b/src/rpc/virkeepalive.c
index 860b91b6b1..119427eb03 100644
--- a/src/rpc/virkeepalive.c
+++ b/src/rpc/virkeepalive.c
@@ -40,8 +40,8 @@ struct _virKeepAlive {
     int interval;
     unsigned int count;
     unsigned int countToDeath;
-    time_t lastPacketReceived;
-    time_t intervalStart;
+    gint64 lastPacketReceived;
+    gint64 intervalStart;
     int timer;
 
     virKeepAliveSendFunc sendCB;
@@ -113,7 +113,7 @@ static bool
 virKeepAliveTimerInternal(virKeepAlivePtr ka,
                           virNetMessagePtr *msg)
 {
-    time_t now = time(NULL);
+    gint64 now = g_get_monotonic_time() / G_USEC_PER_SEC;
     int timeval;
 
     if (ka->interval <= 0 || ka->intervalStart == 0)
@@ -231,9 +231,9 @@ virKeepAliveStart(virKeepAlivePtr ka,
                   unsigned int count)
 {
     int ret = -1;
-    time_t delay;
+    gint64 delay;
     int timeout;
-    time_t now;
+    gint64 now;
 
     virObjectLock(ka);
 
@@ -270,7 +270,7 @@ virKeepAliveStart(virKeepAlivePtr ka,
           "ka=%p client=%p interval=%d count=%u",
           ka, ka->client, interval, count);
 
-    now = time(NULL);
+    now = g_get_monotonic_time() / G_USEC_PER_SEC;
     delay = now - ka->lastPacketReceived;
     if (delay > ka->interval)
         timeout = 0;
@@ -375,7 +375,8 @@ virKeepAliveCheckMessage(virKeepAlivePtr ka,
     virObjectLock(ka);
 
     ka->countToDeath = ka->count;
-    ka->lastPacketReceived = ka->intervalStart = time(NULL);
+    ka->intervalStart = g_get_monotonic_time() / G_USEC_PER_SEC;
+    ka->lastPacketReceived = ka->intervalStart;
 
     if (msg->header.prog == KEEPALIVE_PROGRAM &&
         msg->header.vers == KEEPALIVE_PROTOCOL_VERSION &&
-- 
2.23.0