[libFuzzer] Instrument bcmp
If we define memcmp in an archive, bcmp should be defined as well (many libc
define bcmp/memcmp in one object file). Otherwise if the application calls bcmp
or strcmp which gets optimized to bcmp (SimplifyLibCalls), the undefined
reference may pull in an optimized bcmp/strcmp implementation (libc replacement)
later on the linker command line. If both libFuzzer's memcmp and the optimized
memcmp are strong => there will be a multiple definition error.
GitOrigin-RevId: f7ffb122d08e7a8203557898c67eaac3a857b152
diff --git a/FuzzerInterceptors.cpp b/FuzzerInterceptors.cpp
index 0afc96c..a1a6478 100644
--- a/FuzzerInterceptors.cpp
+++ b/FuzzerInterceptors.cpp
@@ -119,6 +119,7 @@
extern "C" {
+DEFINE_REAL(int, bcmp, const void *, const void *, size_t)
DEFINE_REAL(int, memcmp, const void *, const void *, size_t)
DEFINE_REAL(int, strncmp, const char *, const char *, size_t)
DEFINE_REAL(int, strcmp, const char *, const char *)
@@ -128,6 +129,14 @@
DEFINE_REAL(char *, strcasestr, const char *, const char *)
DEFINE_REAL(void *, memmem, const void *, size_t, const void *, size_t)
+ATTRIBUTE_INTERFACE int bcmp(const char *s1, const char *s2, size_t n) {
+ if (!FuzzerInited)
+ return internal_memcmp(s1, s2, n);
+ int result = REAL(bcmp)(s1, s2, n);
+ __sanitizer_weak_hook_memcmp(GET_CALLER_PC(), s1, s2, n, result);
+ return result;
+}
+
ATTRIBUTE_INTERFACE int memcmp(const void *s1, const void *s2, size_t n) {
if (!FuzzerInited)
return internal_memcmp(s1, s2, n);
@@ -200,6 +209,8 @@
return;
FuzzerInitIsRunning = true;
+ REAL(bcmp) = reinterpret_cast<memcmp_type>(
+ getFuncAddr("bcmp", reinterpret_cast<uintptr_t>(&bcmp)));
REAL(memcmp) = reinterpret_cast<memcmp_type>(
getFuncAddr("memcmp", reinterpret_cast<uintptr_t>(&memcmp)));
REAL(strncmp) = reinterpret_cast<strncmp_type>(
