From 55642519202158866a46ad2b2408a874fcc0cd4c Mon Sep 17 00:00:00 2001
From: Christian Reitter <invd@inhq.net>
Date: Sat, 13 Nov 2021 14:25:32 +0100
Subject: [PATCH] feat(crypto): improve fuzzer secp256k1-zkp integration, add
 build workaround and sanitizer optimization, minor renaming

---
 crypto/Makefile                        |  7 +++++++
 crypto/fuzzer/README.md                |  2 ++
 crypto/fuzzer/fuzzer.c                 | 18 +++++++++---------
 crypto/fuzzer/sanitizer_ignorelist.txt | 21 +++++++++++++++++++++
 4 files changed, 39 insertions(+), 9 deletions(-)
 create mode 100644 crypto/fuzzer/sanitizer_ignorelist.txt

diff --git a/crypto/Makefile b/crypto/Makefile
index 9fbb9f63a..e9fc3867e 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -2,6 +2,13 @@ ifeq ($(FUZZER),1)
 CC       ?= clang
 LD       ?= $(CC)
 SANFLAGS += -fsanitize=fuzzer
+CFLAGS   += -fsanitize-ignorelist=fuzzer/sanitizer_ignorelist.txt
+
+# this works around clang optimization issues in relation with -fsanitize=undefined
+# TODO is there a better solution, for example by disabling a specific optimization technique?
+blake2b.o: OPTFLAGS += -O0
+blake2s.o: OPTFLAGS += -O0
+
 else ifeq ($(ADDRESS_SANITIZER),1)
 SANFLAGS += -fsanitize=address,undefined
 endif
diff --git a/crypto/fuzzer/README.md b/crypto/fuzzer/README.md
index a0dd358cf..217aeee24 100644
--- a/crypto/fuzzer/README.md
+++ b/crypto/fuzzer/README.md
@@ -30,6 +30,8 @@ Examples:
   * `OPTFLAGS="-O0 -ggdb3"`
   * `OPTFLAGS="-O3 -march=native"`
 
+To be determined: use of `-fsanitize-ignorelist` to reduce sanitizer overhead on hot functions
+
 ### Other Flags
 
 To be determined:
diff --git a/crypto/fuzzer/fuzzer.c b/crypto/fuzzer/fuzzer.c
index c79a1af64..3b205fdc8 100644
--- a/crypto/fuzzer/fuzzer.c
+++ b/crypto/fuzzer/fuzzer.c
@@ -381,19 +381,19 @@ int fuzz_nem_validate_address(void) {
 }
 
 int fuzz_nem_get_address(void) {
-  unsigned char ed25519_public_key[32] = {0};
+  unsigned char ed25519_public_key_fuzz[32] = {0};
   uint32_t network = 0;
 
-  if (fuzzer_length != (sizeof(ed25519_public_key) + sizeof(network))) {
+  if (fuzzer_length != (sizeof(ed25519_public_key_fuzz) + sizeof(network))) {
     return 0;
   }
 
   char address[NEM_ADDRESS_SIZE + 1] = {0};
 
-  memcpy(ed25519_public_key, fuzzer_input(32), 32);
+  memcpy(ed25519_public_key_fuzz, fuzzer_input(32), 32);
   memcpy(&network, fuzzer_input(4), 4);
 
-  nem_get_address(ed25519_public_key, network, address);
+  nem_get_address(ed25519_public_key_fuzz, network, address);
 
 #if defined(__has_feature)
 #if __has_feature(memory_sanitizer)
@@ -616,15 +616,15 @@ int fuzz_slip39_word_completion_mask(void) {
 }
 
 int fuzz_mnemonic_to_bits(void) {
-  // length chosen somewhat arbitrarily
-#define MAX_MNEMONIC_LENGTH 256
+  // regular MAX_MNEMONIC_LEN is 240, try some extra bytes
+#define MAX_MNEMONIC_FUZZ_LENGTH 256
 
-  if (fuzzer_length < MAX_MNEMONIC_LENGTH) {
+  if (fuzzer_length < MAX_MNEMONIC_FUZZ_LENGTH) {
     return 0;
   }
 
-  char mnemonic[MAX_MNEMONIC_LENGTH + 1] = {0};
-  memcpy(&mnemonic, fuzzer_ptr, MAX_MNEMONIC_LENGTH);
+  char mnemonic[MAX_MNEMONIC_FUZZ_LENGTH + 1] = {0};
+  memcpy(&mnemonic, fuzzer_ptr, MAX_MNEMONIC_FUZZ_LENGTH);
   uint8_t mnemonic_bits[32 + 1] = {0};
 
   mnemonic_to_bits((const char *)&mnemonic, mnemonic_bits);
diff --git a/crypto/fuzzer/sanitizer_ignorelist.txt b/crypto/fuzzer/sanitizer_ignorelist.txt
new file mode 100644
index 000000000..b0ba86a04
--- /dev/null
+++ b/crypto/fuzzer/sanitizer_ignorelist.txt
@@ -0,0 +1,21 @@
+# ignore bignum math operations and other hot crypto primitives
+
+fun:*sha256_Update*
+fun:*sha256_Raw*
+fun:*sha256_Transform*
+fun:*sha512_Transform*
+fun:*pbkdf2_hmac_sha512_Update*
+fun:*pbkdf2_*
+fun:*hmac_*
+fun:*sha256_*
+# TODO this is very broad
+fun:*bn_*
+fun:*bn_inverse*
+fun:*bn_multiply*
+fun:*bn_multiply_long*
+fun:*bn_multiply_reduce_step*
+fun:*bn_multiply_step*
+fun:*curve25519_mul*
+fun:*point_multiply*
+fun:*point_jacobian_add*
+fun:*scalar_multiply*