Fix PKCS7_verify to not have an error stack if it succeeds.

Revert a change in behavior to BIO_write(). If a NULL BIO
is passed, no error is raised and the return value is 0. There are
many places where the return code from the write was not checked,
resulting in an error stack with no error status being returned.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/15493)

1 files changed, 7 insertions, 4 deletions

diff --git a/crypto/bio/bio_lib.c b/crypto/bio/bio_lib.c
index 91db2290c4..80b81db5c4 100644
--- a/crypto/bio/bio_lib.c
+++ b/crypto/bio/bio_lib.c
@@ -334,10 +334,13 @@ static int bio_write_intern(BIO *b, const void *data, size_t dlen,
 {
     int ret;
 
-    if (b == NULL) {
-        ERR_raise(ERR_LIB_BIO, ERR_R_PASSED_NULL_PARAMETER);
-        return -1;
-    }
+    /*
+     * b == NULL is not an error but just means that zero bytes are written.
+     * Do not raise an error here.
+     */
+    if (b == NULL)
+        return 0;
+
     if (b->method == NULL || b->method->bwrite == NULL) {
         ERR_raise(ERR_LIB_BIO, BIO_R_UNSUPPORTED_METHOD);
         return -2;