[libFuzzer] use data-flow feedback from strcmp

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@244084 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/docs/LibFuzzer.rst b/docs/LibFuzzer.rst
index 3b074aad6a137fc702d0c3ad7286be51e6afa0b2..0eabb5d80694f601560c66bbaa6b8bac2a60ba0f 100644 (file)
--- a/docs/LibFuzzer.rst
+++ b/docs/LibFuzzer.rst
@@ -282,7 +282,7 @@ Data-flow-guided fuzzing
 With an additional compiler flag ``-fsanitize-coverage=trace-cmp`` (see SanitizerCoverageTraceDataFlow_)
 and extra run-time flag ``-use_traces=1`` the fuzzer will try to apply *data-flow-guided fuzzing*.
 That is, the fuzzer will record the inputs to comparison instructions, switch statements,
-and several libc functions (``memcmp``, ``strncmp``, etc).
+and several libc functions (``memcmp``, ``strcmp``, ``strncmp``, etc).
 It will later use those recorded inputs during mutations.
 
 This mode can be combined with DataFlowSanitizer_ to achieve better sensitivity.

diff --git a/lib/Fuzzer/FuzzerTraceState.cpp b/lib/Fuzzer/FuzzerTraceState.cpp
index 1c01e8aa77baee95d22e88af5629e7860fbc634d..13635a70d76b75a5fd031c521afac96d27c416d4 100644 (file)
--- a/lib/Fuzzer/FuzzerTraceState.cpp
+++ b/lib/Fuzzer/FuzzerTraceState.cpp
@@ -356,8 +356,9 @@ void TraceState::TraceCmpCallback(uintptr_t PC, size_t CmpSize, size_t CmpType,
   CSP->Counter[ComputeCmp(CmpSize, CmpType, Arg1, Arg2)]++;
   size_t C0 = CSP->Counter[0];
   size_t C1 = CSP->Counter[1];
-  if (!CSP->IsInterestingCmpTarget())
-    return;
+  // FIXME: is this a good idea or a bad?
+  // if (!CSP->IsInterestingCmpTarget())
+  //  return;
   if (Options.Verbosity >= 3)
     Printf("TraceCmp: %p %zd/%zd; %zd %zd\n", CSP->PC, C0, C1, Arg1, Arg2);
   Added += TryToAddDesiredData(Arg1, Arg2, CmpSize);
@@ -479,6 +480,23 @@ void dfsan_weak_hook_strncmp(void *caller_pc, const char *s1, const char *s2,
   TS->DFSanCmpCallback(PC, n, fuzzer::ICMP_EQ, S1, S2, L1, L2);
 }
 
+void dfsan_weak_hook_strcmp(void *caller_pc, const char *s1, const char *s2,
+                            dfsan_label s1_label, dfsan_label s2_label) {
+  if (!TS) return;
+  uintptr_t PC = reinterpret_cast<uintptr_t>(caller_pc);
+  uint64_t S1 = 0, S2 = 0;
+  size_t Len1 = strlen(s1);
+  size_t Len2 = strlen(s2);
+  size_t N = std::min(Len1, Len2);
+  if (N <= 1) return;  // Not interesting.
+  // Simplification: handle only first 8 bytes.
+  memcpy(&S1, s1, std::min(N, sizeof(S1)));
+  memcpy(&S2, s2, std::min(N, sizeof(S2)));
+  dfsan_label L1 = dfsan_read_label(s1, Len1);
+  dfsan_label L2 = dfsan_read_label(s2, Len2);
+  TS->DFSanCmpCallback(PC, N, fuzzer::ICMP_EQ, S1, S2, L1, L2);
+}
+
 void __sanitizer_weak_hook_memcmp(void *caller_pc, const void *s1,
                                   const void *s2, size_t n) {
   if (!TS) return;
@@ -506,6 +524,22 @@ void __sanitizer_weak_hook_strncmp(void *caller_pc, const char *s1,
   TS->TraceCmpCallback(PC, n, fuzzer::ICMP_EQ, S1, S2);
 }
 
+void __sanitizer_weak_hook_strcmp(void *caller_pc, const char *s1,
+                                   const char *s2) {
+  if (!TS) return;
+  uintptr_t PC = reinterpret_cast<uintptr_t>(caller_pc);
+  uint64_t S1 = 0, S2 = 0;
+  size_t Len1 = strlen(s1);
+  size_t Len2 = strlen(s2);
+  size_t N = std::min(Len1, Len2);
+  if (N <= 1) return;  // Not interesting.
+  // Simplification: handle only first 8 bytes.
+  memcpy(&S1, s1, std::min(N, sizeof(S1)));
+  memcpy(&S2, s2, std::min(N, sizeof(S2)));
+  TS->TraceCmpCallback(PC, N, fuzzer::ICMP_EQ, S1, S2);
+}
+
+
 void __sanitizer_cov_trace_cmp(uint64_t SizeAndType, uint64_t Arg1,
                                uint64_t Arg2) {
   if (!TS) return;

diff --git a/lib/Fuzzer/test/CMakeLists.txt b/lib/Fuzzer/test/CMakeLists.txt
index b8c1f3228df008a17e838d6ac89a7055c05044e6..893274df9a56d28777208335cf2979322b4e9aee 100644 (file)
--- a/lib/Fuzzer/test/CMakeLists.txt
+++ b/lib/Fuzzer/test/CMakeLists.txt
@@ -7,6 +7,7 @@ set(CMAKE_CXX_FLAGS_RELEASE "${LIBFUZZER_FLAGS_BASE} -O0 -fsanitize-coverage=edg
 set(DFSanTests
   MemcmpTest
   SimpleCmpTest
+  StrcmpTest
   StrncmpTest
   SwitchTest
   )
@@ -21,6 +22,7 @@ set(Tests
   NullDerefTest
   SimpleCmpTest
   SimpleTest
+  StrcmpTest
   StrncmpTest
   SwitchTest
   TimeoutTest

diff --git a/lib/Fuzzer/test/fuzzer-dfsan.test b/lib/Fuzzer/test/fuzzer-dfsan.test
index 266cb51a594397862cfb2a1dd4291d9270afbef9..d6820323710813972d1a4ec005d5ca9f28c7569e 100644 (file)
--- a/lib/Fuzzer/test/fuzzer-dfsan.test
+++ b/lib/Fuzzer/test/fuzzer-dfsan.test
@@ -15,5 +15,8 @@ RUN: LLVMFuzzer-MemcmpTest-DFSan -use_traces=1 -seed=1 -runs=2 -timeout=5 -verbo
 RUN: not LLVMFuzzer-StrncmpTest-DFSan -use_traces=1 -seed=1 -runs=10000 -timeout=5 2>&1 | FileCheck %s --check-prefix=CHECK3
 RUN: LLVMFuzzer-StrncmpTest-DFSan -use_traces=1 -seed=1 -runs=2 -timeout=5 -verbosity=3 2>&1 | FileCheck %s  -check-prefix=CHECK_DFSanCmpCallback
 
+RUN: not LLVMFuzzer-StrcmpTest-DFSan -use_traces=1 -seed=1 -runs=10000 -timeout=5 2>&1 | FileCheck %s --check-prefix=CHECK3
+RUN:     LLVMFuzzer-StrcmpTest-DFSan -use_traces=1 -seed=1 -runs=2     -timeout=5 -verbosity=3 2>&1 | FileCheck %s  -check-prefix=CHECK_DFSanCmpCallback
+
 RUN: not LLVMFuzzer-SwitchTest-DFSan -use_traces=1 -seed=1 -runs=100000 -timeout=5              2>&1 | FileCheck %s --check-prefix=CHECK4
 RUN:     LLVMFuzzer-SwitchTest-DFSan -use_traces=1 -seed=1 -runs=2     -timeout=5 -verbosity=3 2>&1 | FileCheck %s  -check-prefix=CHECK_DFSanSwitchCallback

diff --git a/lib/Fuzzer/test/fuzzer.test b/lib/Fuzzer/test/fuzzer.test
index bfb5849bba829ad9945b0e37e63c1eed4dbdf6f3..83fc0f88caa9c9b54bd1dd6dd0d85f6241629f78 100644 (file)
--- a/lib/Fuzzer/test/fuzzer.test
+++ b/lib/Fuzzer/test/fuzzer.test
@@ -32,5 +32,8 @@ Done1000000: Done 1000000 runs in
 RUN: not LLVMFuzzer-StrncmpTest -use_traces=1 -seed=1 -runs=10000    2>&1 | FileCheck %s
 RUN:     LLVMFuzzer-StrncmpTest               -seed=1 -runs=1000000  2>&1 | FileCheck %s --check-prefix=Done1000000
 
+RUN: not LLVMFuzzer-StrcmpTest -use_traces=1 -seed=1 -runs=10000    2>&1 | FileCheck %s
+RUN:     LLVMFuzzer-StrcmpTest               -seed=1 -runs=1000000  2>&1 | FileCheck %s --check-prefix=Done1000000
+
 RUN: not LLVMFuzzer-SwitchTest -use_traces=1 -seed=1 -runs=1000000  2>&1 | FileCheck %s
 RUN:     LLVMFuzzer-SwitchTest               -seed=1 -runs=1000000  2>&1 | FileCheck %s --check-prefix=Done1000000