fix(auth): forbid junk after extensions
The extensions must use all remaining bytes in the TBSCertificate.
Change-Id: Idf48f7168e146d050ba62dbc732638946fcd6c92
Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
diff --git a/drivers/auth/mbedtls/mbedtls_x509_parser.c b/drivers/auth/mbedtls/mbedtls_x509_parser.c
index 49bc008..8c78003 100644
--- a/drivers/auth/mbedtls/mbedtls_x509_parser.c
+++ b/drivers/auth/mbedtls/mbedtls_x509_parser.c
@@ -304,24 +304,26 @@
/*
* extensions [3] EXPLICIT Extensions OPTIONAL
+ * -- must use all remaining bytes in TBSCertificate
*/
ret = mbedtls_asn1_get_tag(&p, end, &len,
MBEDTLS_ASN1_CONTEXT_SPECIFIC |
MBEDTLS_ASN1_CONSTRUCTED | 3);
- if (ret != 0) {
+ if ((ret != 0) || (len != (size_t)(end - p))) {
return IMG_PARSER_ERR_FORMAT;
}
/*
* Extensions ::= SEQUENCE SIZE (1..MAX) OF Extension
+ * -- must use all remaining bytes in TBSCertificate
*/
v3_ext.p = p;
ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_ASN1_SEQUENCE);
- if (ret != 0) {
+ if ((ret != 0) || (len != (size_t)(end - p))) {
return IMG_PARSER_ERR_FORMAT;
}
- v3_ext.len = (p + len) - v3_ext.p;
+ v3_ext.len = end - v3_ext.p;
/*
* Check extensions integrity