From 94c0cfbb82980439003713b8fcb7ae78859be069 Mon Sep 17 00:00:00 2001 From: Demi Marie Obenour Date: Thu, 8 Dec 2022 15:24:18 -0500 Subject: [PATCH] refactor(auth): partially validate SubjectPublicKeyInfo early This reduces the likelihood of future problems later. Change-Id: Ia748b6ae31a7a48f17ec7f0fc08310a50cd1b135 Signed-off-by: Demi Marie Obenour --- drivers/auth/mbedtls/mbedtls_x509_parser.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/drivers/auth/mbedtls/mbedtls_x509_parser.c b/drivers/auth/mbedtls/mbedtls_x509_parser.c index 9cccd964d..244f1c95e 100644 --- a/drivers/auth/mbedtls/mbedtls_x509_parser.c +++ b/drivers/auth/mbedtls/mbedtls_x509_parser.c @@ -144,7 +144,7 @@ static int cert_parse(void *img, unsigned int img_len) { int ret, is_critical; size_t len; - unsigned char *p, *end, *crt_end; + unsigned char *p, *end, *crt_end, *pk_end; mbedtls_asn1_buf sig_alg1, sig_alg2; /* * The unique ASN.1 DER encoding of [0] EXPLICIT INTEGER { v3(2} }. @@ -271,9 +271,22 @@ static int cert_parse(void *img, unsigned int img_len) if (ret != 0) { return IMG_PARSER_ERR_FORMAT; } - pk.len = (p + len) - pk.p; + pk_end = p + len; + pk.len = pk_end - pk.p; + + ret = mbedtls_asn1_get_tag(&p, pk_end, &len, MBEDTLS_ASN1_CONSTRUCTED | + MBEDTLS_ASN1_SEQUENCE); + if (ret != 0) { + return IMG_PARSER_ERR_FORMAT; + } p += len; + ret = mbedtls_asn1_get_tag(&p, pk_end, &len, MBEDTLS_ASN1_BIT_STRING); + if ((ret != 0) || (p + len != pk_end)) { + return IMG_PARSER_ERR_FORMAT; + } + p = pk_end; + /* * issuerUniqueID [1] IMPLICIT UniqueIdentifier OPTIONAL, */ -- 2.39.5