From 5baf9dc2fbb459828b4102b0a1c5214879434c03 Mon Sep 17 00:00:00 2001 From: gVisor bot Date: Fri, 14 Feb 2020 15:48:09 -0800 Subject: Synchronize signalling with S/R This is to fix a data race between sending an external signal to a ThreadGroup and kernel saving state for S/R. PiperOrigin-RevId: 295244281 --- pkg/sentry/kernel/kernel.go | 8 ++++++++ runsc/boot/loader.go | 8 ++++---- 2 files changed, 12 insertions(+), 4 deletions(-) diff --git a/pkg/sentry/kernel/kernel.go b/pkg/sentry/kernel/kernel.go index ea21af33f..7da0368f1 100644 --- a/pkg/sentry/kernel/kernel.go +++ b/pkg/sentry/kernel/kernel.go @@ -1169,6 +1169,14 @@ func (k *Kernel) SendExternalSignal(info *arch.SignalInfo, context string) { k.sendExternalSignal(info, context) } +// SendExternalSignalThreadGroup injects a signal into an specific ThreadGroup. +// This function doesn't skip signals like SendExternalSignal does. +func (k *Kernel) SendExternalSignalThreadGroup(tg *ThreadGroup, info *arch.SignalInfo) error { + k.extMu.Lock() + defer k.extMu.Unlock() + return tg.SendSignal(info) +} + // SendContainerSignal sends the given signal to all processes inside the // namespace that match the given container ID. func (k *Kernel) SendContainerSignal(cid string, info *arch.SignalInfo) error { diff --git a/runsc/boot/loader.go b/runsc/boot/loader.go index 239ca5302..eef43b9df 100644 --- a/runsc/boot/loader.go +++ b/runsc/boot/loader.go @@ -997,7 +997,7 @@ func (l *Loader) signalProcess(cid string, tgid kernel.ThreadID, signo int32) er execTG, _, err := l.threadGroupFromID(execID{cid: cid, pid: tgid}) if err == nil { // Send signal directly to the identified process. - return execTG.SendSignal(&arch.SignalInfo{Signo: signo}) + return l.k.SendExternalSignalThreadGroup(execTG, &arch.SignalInfo{Signo: signo}) } // The caller may be signaling a process not started directly via exec. @@ -1014,7 +1014,7 @@ func (l *Loader) signalProcess(cid string, tgid kernel.ThreadID, signo int32) er if tg.Leader().ContainerID() != cid { return fmt.Errorf("process %d is part of a different container: %q", tgid, tg.Leader().ContainerID()) } - return tg.SendSignal(&arch.SignalInfo{Signo: signo}) + return l.k.SendExternalSignalThreadGroup(tg, &arch.SignalInfo{Signo: signo}) } func (l *Loader) signalForegrondProcessGroup(cid string, tgid kernel.ThreadID, signo int32) error { @@ -1032,7 +1032,7 @@ func (l *Loader) signalForegrondProcessGroup(cid string, tgid kernel.ThreadID, s // No foreground process group has been set. Signal the // original thread group. log.Warningf("No foreground process group for container %q and PID %d. Sending signal directly to PID %d.", cid, tgid, tgid) - return tg.SendSignal(&arch.SignalInfo{Signo: signo}) + return l.k.SendExternalSignalThreadGroup(tg, &arch.SignalInfo{Signo: signo}) } // Send the signal to all processes in the process group. var lastErr error @@ -1040,7 +1040,7 @@ func (l *Loader) signalForegrondProcessGroup(cid string, tgid kernel.ThreadID, s if tg.ProcessGroup() != pg { continue } - if err := tg.SendSignal(&arch.SignalInfo{Signo: signo}); err != nil { + if err := l.k.SendExternalSignalThreadGroup(tg, &arch.SignalInfo{Signo: signo}); err != nil { lastErr = err } } -- cgit v1.2.3