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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/key.cpp
parent0b019357ff09e7a522307fc271d6b60562a7b890 (diff)
Fix potential overflows in ECDSA DER parsers
Diffstat (limited to 'src/key.cpp')
-rw-r--r--src/key.cpp32
1 files changed, 19 insertions, 13 deletions
diff --git a/src/key.cpp b/src/key.cpp
index 5a991fc1d2..f581bcb0c8 100644
--- a/src/key.cpp
+++ b/src/key.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.
@@ -18,41 +19,46 @@ static secp256k1_context* secp256k1_context_sign = NULL;
/** These functions are taken from the libsecp256k1 distribution and are very ugly. */
static int ec_privkey_import_der(const secp256k1_context* ctx, unsigned char *out32, const unsigned char *privkey, size_t privkeylen) {
const unsigned char *end = privkey + privkeylen;
- int lenb = 0;
- int len = 0;
+ size_t lenb = 0;
+ size_t len = 0;
memset(out32, 0, 32);
/* sequence header */
- if (end < privkey+1 || *privkey != 0x30) {
+ if (end - privkey < 1 || *privkey != 0x30u) {
return 0;
}
privkey++;
/* sequence length constructor */
- if (end < privkey+1 || !(*privkey & 0x80)) {
+ if (end - privkey < 1 || !(*privkey & 0x80u)) {
return 0;
}
- lenb = *privkey & ~0x80; privkey++;
+ lenb = *privkey & ~0x80u; privkey++;
if (lenb < 1 || lenb > 2) {
return 0;
}
- if (end < privkey+lenb) {
+ if (end - privkey < lenb) {
return 0;
}
/* sequence length */
- len = privkey[lenb-1] | (lenb > 1 ? privkey[lenb-2] << 8 : 0);
+ len = privkey[lenb-1] | (lenb > 1 ? privkey[lenb-2] << 8 : 0u);
privkey += lenb;
- if (end < privkey+len) {
+ if (end - privkey < len) {
return 0;
}
/* sequence element 0: version number (=1) */
- if (end < privkey+3 || privkey[0] != 0x02 || privkey[1] != 0x01 || privkey[2] != 0x01) {
+ if (end - privkey < 3 || privkey[0] != 0x02u || privkey[1] != 0x01u || privkey[2] != 0x01u) {
return 0;
}
privkey += 3;
/* sequence element 1: octet string, up to 32 bytes */
- if (end < privkey+2 || privkey[0] != 0x04 || privkey[1] > 0x20 || end < privkey+2+privkey[1]) {
+ if (end - privkey < 2 || privkey[0] != 0x04u) {
return 0;
}
- memcpy(out32 + 32 - privkey[1], privkey + 2, privkey[1]);
+ size_t oslen = privkey[1];
+ privkey += 2;
+ if (oslen > 32 || end - privkey < oslen) {
+ return 0;
+ }
+ memcpy(out32 + (32 - oslen), privkey, oslen);
if (!secp256k1_ec_seckey_verify(ctx, out32)) {
memset(out32, 0, 32);
return 0;
@@ -219,10 +225,10 @@ bool CKey::Derive(CKey& keyChild, ChainCode &ccChild, unsigned int nChild, const
std::vector<unsigned char, secure_allocator<unsigned char>> vout(64);
if ((nChild >> 31) == 0) {
CPubKey pubkey = GetPubKey();
- assert(pubkey.begin() + 33 == pubkey.end());
+ assert(pubkey.size() == 33);
BIP32Hash(cc, nChild, *pubkey.begin(), pubkey.begin()+1, vout.data());
} else {
- assert(begin() + 32 == end());
+ assert(size() == 32);
BIP32Hash(cc, nChild, 0, begin(), vout.data());
}
memcpy(ccChild.begin(), vout.data()+32, 32);