From 0e3a930fb402cf9785c2acbddf015574d30cb6b5 Mon Sep 17 00:00:00 2001 From: "Dr. Stephen Henson" Date: Wed, 4 Jan 2012 18:44:20 +0000 Subject: [PATCH] Prevent malformed RFC3779 data triggering an assertion failure (CVE-2011-4577) --- CHANGES | 5 +++ crypto/x509v3/v3_addr.c | 74 +++++++++++++++++++++++++---------------- 2 files changed, 50 insertions(+), 29 deletions(-) diff --git a/CHANGES b/CHANGES index 8c9fd59be0..a6672ed6fe 100644 --- a/CHANGES +++ b/CHANGES @@ -3,6 +3,11 @@ _______________ Changes between 0.9.8r and 0.9.8s [xx XXX xxxx] + + *) Prevent malformed RFC3779 data triggering an assertion failure. + Thanks to Andrew Chi, BBN Technologies, for discovering the flaw + and Rob Austein for fixing it. (CVE-2011-4577) + [Rob Austein ] *) Fix ssl_ciph.c set-up race. [Adam Langley (Google)] diff --git a/crypto/x509v3/v3_addr.c b/crypto/x509v3/v3_addr.c index d27a707407..c0e1d2d142 100644 --- a/crypto/x509v3/v3_addr.c +++ b/crypto/x509v3/v3_addr.c @@ -142,12 +142,13 @@ unsigned int v3_addr_get_afi(const IPAddressFamily *f) * Expand the bitstring form of an address into a raw byte array. * At the moment this is coded for simplicity, not speed. */ -static void addr_expand(unsigned char *addr, +static int addr_expand(unsigned char *addr, const ASN1_BIT_STRING *bs, const int length, const unsigned char fill) { - OPENSSL_assert(bs->length >= 0 && bs->length <= length); + if (bs->length < 0 || bs->length > length) + return 0; if (bs->length > 0) { memcpy(addr, bs->data, bs->length); if ((bs->flags & 7) != 0) { @@ -159,6 +160,7 @@ static void addr_expand(unsigned char *addr, } } memset(addr + bs->length, fill, length - bs->length); + return 1; } /* @@ -181,15 +183,13 @@ static int i2r_address(BIO *out, return 0; switch (afi) { case IANA_AFI_IPV4: - if (bs->length > 4) + if (!addr_expand(addr, bs, 4, fill)) return 0; - addr_expand(addr, bs, 4, fill); BIO_printf(out, "%d.%d.%d.%d", addr[0], addr[1], addr[2], addr[3]); break; case IANA_AFI_IPV6: - if (bs->length > 16) + if (!addr_expand(addr, bs, 16, fill)) return 0; - addr_expand(addr, bs, 16, fill); for (n = 16; n > 1 && addr[n-1] == 0x00 && addr[n-2] == 0x00; n -= 2) ; for (i = 0; i < n; i += 2) @@ -315,6 +315,12 @@ static int i2r_IPAddrBlocks(X509V3_EXT_METHOD *method, /* * Sort comparison function for a sequence of IPAddressOrRange * elements. + * + * There's no sane answer we can give if addr_expand() fails, and an + * assertion failure on externally supplied data is seriously uncool, + * so we just arbitrarily declare that if given invalid inputs this + * function returns -1. If this messes up your preferred sort order + * for garbage input, tough noogies. */ static int IPAddressOrRange_cmp(const IPAddressOrRange *a, const IPAddressOrRange *b, @@ -327,22 +333,26 @@ static int IPAddressOrRange_cmp(const IPAddressOrRange *a, switch (a->type) { case IPAddressOrRange_addressPrefix: - addr_expand(addr_a, a->u.addressPrefix, length, 0x00); + if (!addr_expand(addr_a, a->u.addressPrefix, length, 0x00)) + return -1; prefixlen_a = addr_prefixlen(a->u.addressPrefix); break; case IPAddressOrRange_addressRange: - addr_expand(addr_a, a->u.addressRange->min, length, 0x00); + if (!addr_expand(addr_a, a->u.addressRange->min, length, 0x00)) + return -1; prefixlen_a = length * 8; break; } switch (b->type) { case IPAddressOrRange_addressPrefix: - addr_expand(addr_b, b->u.addressPrefix, length, 0x00); + if (!addr_expand(addr_b, b->u.addressPrefix, length, 0x00)) + return -1; prefixlen_b = addr_prefixlen(b->u.addressPrefix); break; case IPAddressOrRange_addressRange: - addr_expand(addr_b, b->u.addressRange->min, length, 0x00); + if (!addr_expand(addr_b, b->u.addressRange->min, length, 0x00)) + return -1; prefixlen_b = length * 8; break; } @@ -658,22 +668,22 @@ int v3_addr_add_range(IPAddrBlocks *addr, /* * Extract min and max values from an IPAddressOrRange. */ -static void extract_min_max(IPAddressOrRange *aor, +static int extract_min_max(IPAddressOrRange *aor, unsigned char *min, unsigned char *max, int length) { - OPENSSL_assert(aor != NULL && min != NULL && max != NULL); + if (aor == NULL || min == NULL || max == NULL) + return 0; switch (aor->type) { case IPAddressOrRange_addressPrefix: - addr_expand(min, aor->u.addressPrefix, length, 0x00); - addr_expand(max, aor->u.addressPrefix, length, 0xFF); - return; + return (addr_expand(min, aor->u.addressPrefix, length, 0x00) && + addr_expand(max, aor->u.addressPrefix, length, 0xFF)); case IPAddressOrRange_addressRange: - addr_expand(min, aor->u.addressRange->min, length, 0x00); - addr_expand(max, aor->u.addressRange->max, length, 0xFF); - return; + return (addr_expand(min, aor->u.addressRange->min, length, 0x00) && + addr_expand(max, aor->u.addressRange->max, length, 0xFF)); } + return 0; } /* @@ -689,9 +699,10 @@ int v3_addr_get_range(IPAddressOrRange *aor, if (aor == NULL || min == NULL || max == NULL || afi_length == 0 || length < afi_length || (aor->type != IPAddressOrRange_addressPrefix && - aor->type != IPAddressOrRange_addressRange)) + aor->type != IPAddressOrRange_addressRange) || + !extract_min_max(aor, min, max, afi_length)) return 0; - extract_min_max(aor, min, max, afi_length); + return afi_length; } @@ -773,8 +784,9 @@ int v3_addr_is_canonical(IPAddrBlocks *addr) IPAddressOrRange *a = sk_IPAddressOrRange_value(aors, j); IPAddressOrRange *b = sk_IPAddressOrRange_value(aors, j + 1); - extract_min_max(a, a_min, a_max, length); - extract_min_max(b, b_min, b_max, length); + if (!extract_min_max(a, a_min, a_max, length) || + !extract_min_max(b, b_min, b_max, length)) + return 0; /* * Punt misordered list, overlapping start, or inverted range. @@ -809,7 +821,8 @@ int v3_addr_is_canonical(IPAddrBlocks *addr) { IPAddressOrRange *a = sk_IPAddressOrRange_value(aors, j); if (a != NULL && a->type == IPAddressOrRange_addressRange) { - extract_min_max(a, a_min, a_max, length); + if (!extract_min_max(a, a_min, a_max, length)) + return 0; if (memcmp(a_min, a_max, length) > 0 || range_should_be_prefix(a_min, a_max, length) >= 0) return 0; @@ -845,8 +858,9 @@ static int IPAddressOrRanges_canonize(IPAddressOrRanges *aors, unsigned char a_min[ADDR_RAW_BUF_LEN], a_max[ADDR_RAW_BUF_LEN]; unsigned char b_min[ADDR_RAW_BUF_LEN], b_max[ADDR_RAW_BUF_LEN]; - extract_min_max(a, a_min, a_max, length); - extract_min_max(b, b_min, b_max, length); + if (!extract_min_max(a, a_min, a_max, length) || + !extract_min_max(b, b_min, b_max, length)) + return 0; /* * Punt inverted ranges. @@ -1132,13 +1146,15 @@ static int addr_contains(IPAddressOrRanges *parent, p = 0; for (c = 0; c < sk_IPAddressOrRange_num(child); c++) { - extract_min_max(sk_IPAddressOrRange_value(child, c), - c_min, c_max, length); + if (!extract_min_max(sk_IPAddressOrRange_value(child, c), + c_min, c_max, length)) + return -1; for (;; p++) { if (p >= sk_IPAddressOrRange_num(parent)) return 0; - extract_min_max(sk_IPAddressOrRange_value(parent, p), - p_min, p_max, length); + if (!extract_min_max(sk_IPAddressOrRange_value(parent, p), + p_min, p_max, length)) + return 0; if (memcmp(p_max, c_max, length) < 0) continue; if (memcmp(p_min, c_min, length) > 0) -- 2.25.1