Optimization and safety precaution in find_issuer() of x509_vfy.c:
candidate issuer cert cannot be the same as the subject cert 'x'
@@ -330,7 +330,11 @@ static X509 *find_issuer(X509_STORE_CTX *ctx, STACK_OF(X509) *sk, X509 *x)
for (i = 0; i < sk_X509_num(sk); i++) {
issuer = sk_X509_value(sk, i);
- if (ctx->check_issued(ctx, x, issuer)) {
+ /*
+ * Below check 'issuer != x' is an optimization and safety precaution:
+ * Candidate issuer cert cannot be the same as the subject cert 'x'.
+ */
+ if (issuer != x && ctx->check_issued(ctx, x, issuer)) {
rv = issuer;
if (x509_check_cert_time(ctx, rv, -1))
break;
