1 // Copyright 2022 Code Intelligence GmbH 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package com.code_intelligence.jazzer.instrumentor 16 17 import org.objectweb.asm.MethodVisitor 18 import org.objectweb.asm.Opcodes 19 20 object DirectByteBufferStrategy : EdgeCoverageStrategy { 21 instrumentControlFlowEdgenull22 override fun instrumentControlFlowEdge( 23 mv: MethodVisitor, 24 edgeId: Int, 25 variable: Int, 26 coverageMapInternalClassName: String, 27 ) { 28 mv.apply { 29 visitVarInsn(Opcodes.ALOAD, variable) 30 // Stack: counters 31 push(edgeId) 32 // Stack: counters | edgeId 33 visitInsn(Opcodes.DUP2) 34 // Stack: counters | edgeId | counters | edgeId 35 visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/nio/ByteBuffer", "get", "(I)B", false) 36 // Increment the counter, but ensure that it never stays at 0 after an overflow by incrementing it again in 37 // that case. 38 // This approach performs better than saturating the counter at 255 (see Section 3.3 of 39 // https://www.usenix.org/system/files/woot20-paper-fioraldi.pdf) 40 // Stack: counters | edgeId | counter (sign-extended to int) 41 push(0xff) 42 // Stack: counters | edgeId | counter (sign-extended to int) | 0x000000ff 43 visitInsn(Opcodes.IAND) 44 // Stack: counters | edgeId | counter (zero-extended to int) 45 push(1) 46 // Stack: counters | edgeId | counter | 1 47 visitInsn(Opcodes.IADD) 48 // Stack: counters | edgeId | counter + 1 49 visitInsn(Opcodes.DUP) 50 // Stack: counters | edgeId | counter + 1 | counter + 1 51 push(8) 52 // Stack: counters | edgeId | counter + 1 | counter + 1 | 8 (maxStack: +5) 53 visitInsn(Opcodes.ISHR) 54 // Stack: counters | edgeId | counter + 1 | 1 if the increment overflowed to 0, 0 otherwise 55 visitInsn(Opcodes.IADD) 56 // Stack: counters | edgeId | counter + 2 if the increment overflowed, counter + 1 otherwise 57 visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/nio/ByteBuffer", "put", "(IB)Ljava/nio/ByteBuffer;", false) 58 // Stack: counters 59 visitInsn(Opcodes.POP) 60 } 61 } 62 63 override val instrumentControlFlowEdgeStackSize = 5 64 65 override val localVariableType get() = "java/nio/ByteBuffer" 66 loadLocalVariablenull67 override fun loadLocalVariable(mv: MethodVisitor, variable: Int, coverageMapInternalClassName: String) { 68 mv.apply { 69 visitFieldInsn( 70 Opcodes.GETSTATIC, 71 coverageMapInternalClassName, 72 "counters", 73 "Ljava/nio/ByteBuffer;", 74 ) 75 // Stack: counters (maxStack: 1) 76 visitVarInsn(Opcodes.ASTORE, variable) 77 } 78 } 79 80 override val loadLocalVariableStackSize = 1 81 } 82