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authorJack Grigg <jack@z.cash>2017-05-03 00:14:55 +1200
committerJack Grigg <jack@z.cash>2017-07-17 11:55:05 -0500
commita3603ac6f07966036e56554cd754a57791a3491a (patch)
tree17b9faaf7c77cf4edbf9cb1907aaf12b89779ebb /src/pubkey.cpp
parent0b019357ff09e7a522307fc271d6b60562a7b890 (diff)
Fix potential overflows in ECDSA DER parsers
Diffstat (limited to 'src/pubkey.cpp')
-rw-r--r--src/pubkey.cpp15
1 files changed, 9 insertions, 6 deletions
diff --git a/src/pubkey.cpp b/src/pubkey.cpp
index 91af4e56f2..da02fec7a2 100644
--- a/src/pubkey.cpp
+++ b/src/pubkey.cpp
@@ -1,4 +1,5 @@
// Copyright (c) 2009-2016 The Bitcoin Core developers
+// Copyright (c) 2017 The Zcash developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -46,7 +47,7 @@ static int ecdsa_signature_parse_der_lax(const secp256k1_context* ctx, secp256k1
lenbyte = input[pos++];
if (lenbyte & 0x80) {
lenbyte -= 0x80;
- if (pos + lenbyte > inputlen) {
+ if (lenbyte > inputlen - pos) {
return 0;
}
pos += lenbyte;
@@ -65,14 +66,15 @@ static int ecdsa_signature_parse_der_lax(const secp256k1_context* ctx, secp256k1
lenbyte = input[pos++];
if (lenbyte & 0x80) {
lenbyte -= 0x80;
- if (pos + lenbyte > inputlen) {
+ if (lenbyte > inputlen - pos) {
return 0;
}
while (lenbyte > 0 && input[pos] == 0) {
pos++;
lenbyte--;
}
- if (lenbyte >= sizeof(size_t)) {
+ static_assert(sizeof(size_t) >= 4, "size_t too small");
+ if (lenbyte >= 4) {
return 0;
}
rlen = 0;
@@ -103,14 +105,15 @@ static int ecdsa_signature_parse_der_lax(const secp256k1_context* ctx, secp256k1
lenbyte = input[pos++];
if (lenbyte & 0x80) {
lenbyte -= 0x80;
- if (pos + lenbyte > inputlen) {
+ if (lenbyte > inputlen - pos) {
return 0;
}
while (lenbyte > 0 && input[pos] == 0) {
pos++;
lenbyte--;
}
- if (lenbyte >= sizeof(size_t)) {
+ static_assert(sizeof(size_t) >= 4, "size_t too small");
+ if (lenbyte >= 4) {
return 0;
}
slen = 0;
@@ -225,7 +228,7 @@ bool CPubKey::Decompress() {
bool CPubKey::Derive(CPubKey& pubkeyChild, ChainCode &ccChild, unsigned int nChild, const ChainCode& cc) const {
assert(IsValid());
assert((nChild >> 31) == 0);
- assert(begin() + 33 == end());
+ assert(size() == 33);
unsigned char out[64];
BIP32Hash(cc, nChild, *begin(), begin()+1, out);
memcpy(ccChild.begin(), out+32, 32);