From b4056f6cfcfee54a6aecd7322518a95d941bbdc0 Mon Sep 17 00:00:00 2001
From: Aleksandr Nogikh <nogikh@google.com>
Date: Tue, 16 Jan 2024 16:17:48 +0100
Subject: syz-ci: limit fuzzing of old kernel images

Introduce a new manager config -- the maximum allowed (non-)freshness of
the kernel image that we fuzz. Once the kernel image is old enough and
we're unable to build a newer version, don't start the instance.

Enforce the restriction only after we have tried to build a newer kernel
and failed.
---
 syz-ci/manager.go | 11 +++++++++++
 syz-ci/syz-ci.go  | 11 +++++++++--
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/syz-ci/manager.go b/syz-ci/manager.go
index dfa6940b5..c19c4cb52 100644
--- a/syz-ci/manager.go
+++ b/syz-ci/manager.go
@@ -88,6 +88,7 @@ type Manager struct {
 	stop           chan struct{}
 	debug          bool
 	lastBuild      *dashapi.Build
+	buildFailed    bool
 }
 
 type ManagerDashapi interface {
@@ -241,6 +242,7 @@ loop:
 
 func (mgr *Manager) pollAndBuild(lastCommit string, latestInfo *BuildInfo) (
 	string, *BuildInfo, time.Duration) {
+	var success bool
 	rebuildAfter := buildRetryPeriod
 	commit, err := mgr.repo.Poll(mgr.mgrcfg.Repo, mgr.mgrcfg.Branch)
 	if err != nil {
@@ -263,6 +265,8 @@ func (mgr *Manager) pollAndBuild(lastCommit string, latestInfo *BuildInfo) (
 					latestInfo = mgr.checkLatest()
 					if latestInfo == nil {
 						mgr.Errorf("failed to read build info after build")
+					} else {
+						success = true
 					}
 				}
 				buildSem.Signal()
@@ -270,6 +274,7 @@ func (mgr *Manager) pollAndBuild(lastCommit string, latestInfo *BuildInfo) (
 			}
 		}
 	}
+	mgr.buildFailed = !success
 	return lastCommit, latestInfo, rebuildAfter
 }
 
@@ -410,6 +415,12 @@ func (mgr *Manager) restartManager() {
 		mgr.Errorf("failed to upload build: %v", err)
 		return
 	}
+	daysSinceCommit := time.Since(info.KernelCommitDate).Hours() / 24
+	if mgr.buildFailed && daysSinceCommit > float64(mgr.mgrcfg.MaxKernelLagDays) {
+		mgr.Errorf("the kernel is now too old (%.1f days since last commit), fuzzing is stopped",
+			daysSinceCommit)
+		return
+	}
 	cfgFile, err := mgr.writeConfig(buildTag)
 	if err != nil {
 		mgr.Errorf("failed to create manager config: %v", err)
diff --git a/syz-ci/syz-ci.go b/syz-ci/syz-ci.go
index 138bf2104..ae6ff0f87 100644
--- a/syz-ci/syz-ci.go
+++ b/syz-ci/syz-ci.go
@@ -199,9 +199,13 @@ type ManagerConfig struct {
 	Jobs         ManagerJobs `json:"jobs"`
 	// Extra commits to cherry pick to older kernel revisions.
 	BisectBackports []vcs.BackportCommit `json:"bisect_backports"`
-
+	// Base syz-manager config for the instance.
 	ManagerConfig json.RawMessage `json:"manager_config"`
-	managercfg    *mgrconfig.Config
+	// If the kernel's commit is older than MaxKernelLagDays days,
+	// fuzzing won't be started on this instance.
+	// By default it's 30 days.
+	MaxKernelLagDays int
+	managercfg       *mgrconfig.Config
 }
 
 type ManagerJobs struct {
@@ -444,6 +448,9 @@ func loadManagerConfig(cfg *Config, mgr *ManagerConfig) error {
 	if mgr.KernelConfig != "" && mgr.KernelBaselineConfig == "" {
 		mgr.KernelBaselineConfig = inferBaselineConfig(mgr.KernelConfig)
 	}
+	if mgr.MaxKernelLagDays == 0 {
+		mgr.MaxKernelLagDays = 30
+	}
 	if err := mgr.validate(cfg); err != nil {
 		return err
 	}
-- 
cgit mrf-deployment