Add appropriate NULL checks in EVP_CIPHER api

The EVP_CIPHER api currently assumes that calls made into several APIs
have already initalized the cipher in a given context via a call to
EVP_CipherInit[_ex[2]].  If that hasnt been done, instead of an error,
the result is typically a SIGSEGV.

Correct that by adding missing NULL checks in the apropriate apis prior
to using ctx->cipher

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22995)

1 files changed, 4 insertions, 0 deletions

diff --git a/crypto/evp/bio_enc.c b/crypto/evp/bio_enc.c
index ece3f6d57f..fc6eec7764 100644
--- a/crypto/evp/bio_enc.c
+++ b/crypto/evp/bio_enc.c
@@ -132,6 +132,10 @@ static int enc_read(BIO *b, char *out, int outl)
     }
 
     blocksize = EVP_CIPHER_CTX_get_block_size(ctx->cipher);
+
+    if (blocksize == 0)
+        return 0;
+
     if (blocksize == 1)
         blocksize = 0;