From: BiaoXiang Ye <yebiaoxiang(a)huawei.com&gt; Setting the system time backward would lead to a multiplication overflow in function virKeepAliveStart. FunctionvirKeepAliveTimerInternal 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(a)huawei.com&gt; --- src/rpc/virkeepalive.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/src/rpc/virkeepalive.c b/src/rpc/virkeepalive.c index 860b91b6b1..e662484ea6 100644 --- a/src/rpc/virkeepalive.c +++ b/src/rpc/virkeepalive.c @@ -119,12 +119,25 @@ virKeepAliveTimerInternal(virKeepAlivePtr ka, if (ka->interval <= 0 || ka->intervalStart == 0) return false; + if (now < ka->intervalStart) { + VIR_WARN("system time jump back detected. now=%ld," + " intervalStart=%ld", + now, ka->intervalStart); + ka->intervalStart = now; + } + if (now - ka->intervalStart < ka->interval) { timeval = ka->interval - (now - ka->intervalStart); virEventUpdateTimeout(ka->timer, timeval * 1000); return false; } + if (now < ka->lastPacketReceived) { + VIR_WARN("system time jump back detected. now=%ld," + " lastPacketReceived=%ld", + now, ka->lastPacketReceived); + ka->lastPacketReceived = now; + } timeval = now - ka->lastPacketReceived; PROBE(RPC_KEEPALIVE_TIMEOUT, "ka=%p client=%p countToDeath=%d idle=%d", @@ -271,6 +284,13 @@ virKeepAliveStart(virKeepAlivePtr ka, ka, ka->client, interval, count); now = time(NULL); + if (now < ka->lastPacketReceived) { + VIR_WARN("system time jump back detected. now=%ld," + " lastPacketReceived=%ld", + now, ka->lastPacketReceived); + ka->lastPacketReceived = now; + } + delay = now - ka->lastPacketReceived; if (delay > ka->interval) timeout = 0; -- 2.23.0