executor, host, csource: Add support to enable KCSAN

By default, the current KCSAN .config does not enable KCSAN during boot,
since we encounter races during boot which would prevent syzkaller from
ever executing.

This adds support to detect if KCSAN is available, and enables it on the
fuzzer host.

2 files changed, 13 insertions, 0 deletions

diff --git a/pkg/host/host.go b/pkg/host/host.go
index c7454d12b..dbd3b9ec3 100644
--- a/pkg/host/host.go
+++ b/pkg/host/host.go
@@ -75,6 +75,7 @@ const (
 	FeatureLeakChecking
 	FeatureNetworkInjection
 	FeatureNetworkDevices
+	FeatureKCSAN
 	numFeatures
 )
 
@@ -106,6 +107,7 @@ func Check(target *prog.Target) (*Features, error) {
 		FeatureLeakChecking:               {Name: "leak checking", Reason: unsupported},
 		FeatureNetworkInjection:           {Name: "net packet injection", Reason: unsupported},
 		FeatureNetworkDevices:             {Name: "net device setup", Reason: unsupported},
+		FeatureKCSAN:                      {Name: "concurrency sanitizer", Reason: unsupported},
 	}
 	switch target.OS {
 	case "akaros", "fuchsia", "test":
@@ -142,6 +144,9 @@ func Setup(target *prog.Target, features *Features, featureFlags csource.Feature
 	if target.OS == "linux" && featureFlags["binfmt_misc"].Enabled {
 		args = append(args, "binfmt_misc")
 	}
+	if features[FeatureKCSAN].Enabled {
+		args = append(args, "kcsan")
+	}
 	_, err := osutil.RunCmd(time.Minute, "", executor, args...)
 	return err
 }
diff --git a/pkg/host/host_linux.go b/pkg/host/host_linux.go
index 25da4b016..da208bbad 100644
--- a/pkg/host/host_linux.go
+++ b/pkg/host/host_linux.go
@@ -395,6 +395,7 @@ func init() {
 	checkFeature[FeatureLeakChecking] = checkLeakChecking
 	checkFeature[FeatureNetworkInjection] = checkNetworkInjection
 	checkFeature[FeatureNetworkDevices] = unconditionallyEnabled
+	checkFeature[FeatureKCSAN] = checkKCSAN
 }
 
 func checkCoverage() string {
@@ -556,3 +557,10 @@ func checkDebugFS() string {
 	}
 	return ""
 }
+
+func checkKCSAN() string {
+	if err := osutil.IsAccessible("/proc/kcsaninfo"); err != nil {
+		return err.Error()
+	}
+	return ""
+}