From 05f61fb27efaf1a3f4cfa1a8d4d62c34e3c8a0fe Mon Sep 17 00:00:00 2001 From: Emilia Kasper Date: Mon, 25 Aug 2014 12:38:16 +0200 Subject: [PATCH] Explicitly check for empty ASN.1 strings in d2i_ECPrivateKey The old code implicitly relies on the ASN.1 code returning a \0-prefixed buffer when the buffer length is 0. Change this to verify explicitly that the ASN.1 string has positive length. Reviewed-by: Dr Stephen Henson (cherry picked from commit 82dc08de54ce443c2a9ac478faffe79e76157795) --- crypto/ec/ec_asn1.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/crypto/ec/ec_asn1.c b/crypto/ec/ec_asn1.c index c2f01c31c4..c6dd440b13 100644 --- a/crypto/ec/ec_asn1.c +++ b/crypto/ec/ec_asn1.c @@ -1179,14 +1179,20 @@ EC_KEY *d2i_ECPrivateKey(EC_KEY **a, const unsigned char **in, long len) if (priv_key->publicKey) { const unsigned char *pub_oct; - size_t pub_oct_len; + int pub_oct_len; pub_oct = M_ASN1_STRING_data(priv_key->publicKey); pub_oct_len = M_ASN1_STRING_length(priv_key->publicKey); - /* save the point conversion form */ + /* The first byte - point conversion form - must be present. */ + if (pub_oct_len <= 0) + { + ECerr(EC_F_D2I_ECPRIVATEKEY, EC_R_BUFFER_TOO_SMALL); + goto err; + } + /* Save the point conversion form. */ ret->conv_form = (point_conversion_form_t)(pub_oct[0] & ~0x01); if (!EC_POINT_oct2point(ret->group, ret->pub_key, - pub_oct, pub_oct_len, NULL)) + pub_oct, (size_t)(pub_oct_len), NULL)) { ECerr(EC_F_D2I_ECPRIVATEKEY, ERR_R_EC_LIB); goto err; -- 2.25.1