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, 2 insertions, 0 deletions

diff --git a/ssl/ssl_ciph.c b/ssl/ssl_ciph.c
index 31c0d5af1d..6e49d6b400 100644
--- a/ssl/ssl_ciph.c
+++ b/ssl/ssl_ciph.c
@@ -2221,6 +2221,8 @@ int ssl_cipher_get_overhead(const SSL_CIPHER *c, size_t *mac_overhead,
             in = 1; /* padding length byte */
             out = EVP_CIPHER_get_iv_length(e_ciph);
             blk = EVP_CIPHER_get_block_size(e_ciph);
+            if (blk == 0)
+                return 0;
         }
     }