fix chronyc getting stuck in infinite loop after clock step

chrony-select-timeout.patch

@@ -0,0 +1,94 @@
+commit d0b24860363a3704e28569ce9a6987717834edea
+Author: Miroslav Lichvar <mlichvar@redhat.com>
+Date:   Tue Dec 5 11:08:24 2017 +0100
+
+    client: don't call select() with invalid timeout
+    
+    If the system clock was stepped forward after chronyc sent a request and
+    before it read the clock in order to calculate the receive timeout,
+    select() could be called with a negative timeout, which resulted in an
+    infinite loop waiting for select() to succeed.
+    
+    Fix the submit_request() function to not call select() with a negative
+    timeout. Also, return immediately on any error of select().
+
+diff --git a/client.c b/client.c
+index 5c3a99e..4e23158 100644
+--- a/client.c
++++ b/client.c
+@@ -1394,9 +1394,16 @@ submit_request(CMD_Request *request, CMD_Reply *reply)
+ 
+     timeout = initial_timeout / 1000.0 * (1U << (n_attempts - 1)) -
+               UTI_DiffTimespecsToDouble(&ts_now, &ts_start);
+-    UTI_DoubleToTimeval(timeout, &tv);
+     DEBUG_LOG("Timeout %f seconds", timeout);
+ 
++    /* Avoid calling select() with an invalid timeout */
++    if (timeout <= 0.0) {
++      new_attempt = 1;
++      continue;
++    }
++
++    UTI_DoubleToTimeval(timeout, &tv);
++
+     FD_ZERO(&rdfd);
+     FD_ZERO(&wrfd);
+     FD_ZERO(&exfd);
+@@ -1410,6 +1417,7 @@ submit_request(CMD_Request *request, CMD_Reply *reply)
+ 
+     if (select_status < 0) {
+       DEBUG_LOG("select failed : %s", strerror(errno));
++      return 0;
+     } else if (select_status == 0) {
+       /* Timeout must have elapsed, try a resend? */
+       new_attempt = 1;
+
+commit 6863e43269fe27ce2744eb643295f31c00ec176d
+Author: Miroslav Lichvar <mlichvar@redhat.com>
+Date:   Tue Dec 12 11:03:04 2017 +0100
+
+    client: avoid reading clock after sending request
+    
+    If chronyc sent a request which caused chronyd to step the clock (e.g.
+    makestep, settime) and the second reading of the clock before calling
+    select() to wait for a response happened after the clock was stepped, a
+    new request could be sent immediately and chronyd would process the same
+    command twice. If the second request failed (e.g. a settime request too
+    close to the first request), chronyc would report an error.
+    
+    Change the submit_request() function to read the clock only once per
+    select() to wait for the first response even when the clock was stepped.
+
+diff --git a/client.c b/client.c
+index a04dcb8..7d1e346 100644
+--- a/client.c
++++ b/client.c
+@@ -1347,15 +1347,15 @@ submit_request(CMD_Request *request, CMD_Reply *reply)
+   new_attempt = 1;
+ 
+   do {
++    if (gettimeofday(&tv, NULL))
++      return 0;
++
+     if (new_attempt) {
+       new_attempt = 0;
+ 
+       if (n_attempts > max_retries)
+         return 0;
+ 
+-      if (gettimeofday(&tv, NULL))
+-        return 0;
+-
+       UTI_TimevalToTimespec(&tv, &ts_start);
+ 
+       UTI_GetRandomBytes(&request->sequence, sizeof (request->sequence));
+@@ -1383,9 +1383,6 @@ submit_request(CMD_Request *request, CMD_Reply *reply)
+       DEBUG_LOG("Sent %d bytes", command_length);
+     }
+ 
+-    if (gettimeofday(&tv, NULL))
+-      return 0;
+-
+     UTI_TimevalToTimespec(&tv, &ts_now);
+ 
+     /* Check if the clock wasn't stepped back */

chrony.spec

@@ -21,6 +21,8 @@ Source10:       https://github.com/mlichvar/clknetsim/archive/%{clknetsim_ver}/c
 
 # add NTP servers from DHCP when starting service
 Patch1:         chrony-service-helper.patch
+# fix chronyc getting stuck in infinite loop after clock step
+Patch2:         chrony-select-timeout.patch
 
 BuildRequires:  libcap-devel libedit-devel nss-devel pps-tools-devel
 %ifarch %{ix86} x86_64 %{arm} aarch64 mipsel mips64el ppc64 ppc64le s390 s390x
@@ -54,6 +56,7 @@ clocks, system real-time clock or manual input as time references.
 %setup -q -n %{name}-%{version}%{?prerelease} -a 10
 %{?gitpatch:%patch0 -p1}
 %patch1 -p1 -b .service-helper
+%patch2 -p1 -b .select-timeout
 
 %{?gitpatch: echo %{version}-%{gitpatch} > version.txt}