pkg/aflow/flow/assessment: add KCSAN bug assessment workflow

Author: dvyukov

pkg/aflow/flow/assessment/assessment.go

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+// Copyright 2025 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+package assessmenet
+
+// Common inputs for bug assessment when we don't have a reproducer.
+type Inputs struct {
+	CrashReport       string
+	KernelRepo        string
+	KernelCommit      string
+	KernelConfig      string
+	CodesearchToolBin string
+}

pkg/aflow/flow/assessment/kcsan.go

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+// Copyright 2025 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+package assessmenet
+
+import (
+	"github.com/google/syzkaller/pkg/aflow"
+	"github.com/google/syzkaller/pkg/aflow/action/kernel"
+	"github.com/google/syzkaller/pkg/aflow/ai"
+	"github.com/google/syzkaller/pkg/aflow/tool/codesearcher"
+)
+
+type KCSANOutputs struct {
+	Benign      bool
+	Explanation string
+}
+
+func init() {
+	aflow.Register[Inputs, KCSANOutputs](
+		ai.WorkflowAssessmentKCSAN,
+		"assess if a KCSAN report is about a benign race that only needs annotations or not",
+		&aflow.Flow{
+			Root: &aflow.Pipeline{
+				Actions: []aflow.Action{
+					kernel.Checkout,
+					kernel.Build,
+					codesearcher.PrepareIndex,
+					&aflow.LLMAgent{
+						Name:  "expert",
+						Reply: "Explanation",
+						Outputs: aflow.LLMOutputs[struct {
+							Benign bool `jsonschema:"If the data race is benign or not."`
+						}](),
+						Temperature: 1,
+						Instruction: instruction,
+						Prompt:      prompt,
+						Tools:       codesearcher.Tools,
+					},
+				},
+			},
+		},
+	)
+}
+
+const instruction = `
+You are an experienced Linux kernel developer tasked with determining if the given kernel bug
+report is actionable or not. Actionable means that it contains enough info to root cause
+the underlying bug, and that the report is self-consistent and makes sense, rather than
+a one-off nonsensical crash induced by a previous memory corruption.
+
+Use the provided tools to confirm any assumptions, what variables/fields being accessed, etc.
+In particular, don't make assumptions about the kernel source code,
+use codesearch tools to read the actual source code.
+
+The bug report is a data race report from KCSAN tool.
+It contains 2 stack traces of the memory accesses that constitute a data race.
+The report would be inconsistent, if the stacks point to different subsystems,
+or if they access different fields.
+The report would be non-actionable, if the underlysing data race is "benign".
+That is, the race is on a simple int/bool or similar field, and the accesses
+are not supposed to be protected by any mutual exclusion primitives.
+Common examples of such "benign" data races are accesses to various flags fields,
+statistics counters, and similar.
+An actionable race is "harmful", that is can lead to corruption/crash even with
+a conservative compiler that compiles memory accesses to primitive types
+effectively as atomic. A common example of a "harmful" data races is race on
+a complex container (list/hashmap/etc), where accesses are supposed to be protected
+by a mutual exclusion primitive.
+In the final reply explain why you think the report is consistent and the data race is harmful.
+`
+
+const prompt = `
+The bug report is:
+
+{{.CrashReport}}
+`