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[Openvpn-devel,S] Change in openvpn[master]: Workaround issue in LibreSSL crashing when enumerating digests/ciphers

Message ID 8d0a0a251e08739204f66849157127fec88eb0cc-HTML@gerrit.openvpn.net
State Superseded
Headers show
Series [Openvpn-devel,S] Change in openvpn[master]: Workaround issue in LibreSSL crashing when enumerating digests/ciphers | expand

Commit Message

flichtenheld (Code Review) May 8, 2024, 6:09 p.m. UTC 
Attention is currently required from: flichtenheld.

Hello flichtenheld,

I'd like you to do a code review.
Please visit

    http://gerrit.openvpn.net/c/openvpn/+/586?usp=email

to review the following change.


Change subject: Workaround issue in LibreSSL crashing when enumerating digests/ciphers
......................................................................

Workaround issue in LibreSSL crashing when enumerating digests/ciphers

OpenBSD/LibreSSL reimplemented EVP_get_cipherbyname/EVP_get_digestbyname
and broke calling EVP_get_cipherbynid/EVP_get_digestbyname with an
invalid nid in the process so that it would segfault.

Workaround but doing that NULL check in OpenVPN instead of leaving it
to the library.

Change-Id: Ia08a9697d0ff41721fb0acf17ccb4cfa23cb3934
Signed-off-by: Arne Schwabe <arne@rfc2549.org>
---
M src/openvpn/crypto_openssl.c
1 file changed, 25 insertions(+), 1 deletion(-)



  git pull ssh://gerrit.openvpn.net:29418/openvpn refs/changes/86/586/1
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Patch

diff --git a/src/openvpn/crypto_openssl.c b/src/openvpn/crypto_openssl.c
index 61c6518..1649ab7 100644
--- a/src/openvpn/crypto_openssl.c
+++ b/src/openvpn/crypto_openssl.c
@@ -387,7 +387,19 @@ 
 #else
     for (int nid = 0; nid < 10000; ++nid)
     {
+#if defined(LIBRESSL_VERSION_NUMBER)
+        /* OpenBSD/LibreSSL reimplemented EVP_get_cipherbyname and broke
+         * calling EVP_get_cipherbynid with an invalid nid in the process
+         * so that it would segfault. */
+        const EVP_CIPHER *cipher = NULL;
+        const char *name = OBJ_nid2sn(nid);
+        if (name)
+        {
+            cipher = EVP_get_cipherbyname(name);
+        }
+#else  /* if defined(LIBRESSL_VERSION_NUMBER) */
         const EVP_CIPHER *cipher = EVP_get_cipherbynid(nid);
+#endif
         /* We cast the const away so we can keep the function prototype
          * compatible with EVP_CIPHER_do_all_provided */
         collect_ciphers((EVP_CIPHER *) cipher, &cipher_list);
@@ -441,7 +453,19 @@ 
 #else
     for (int nid = 0; nid < 10000; ++nid)
     {
+        /* OpenBSD/LibreSSL reimplemented EVP_get_digestbyname and broke
+         * calling EVP_get_digestbynid with an invalid nid in the process
+         * so that it would segfault. */
+#ifdef LIBRESSL_VERSION_NUMBER
+        const EVP_MD *digest = NULL;
+        const char *name = OBJ_nid2sn(nid);
+        if (name)
+        {
+            digest = EVP_get_digestbyname(name);
+        }
+#else  /* ifdef LIBRESSL_VERSION_NUMBER */
         const EVP_MD *digest = EVP_get_digestbynid(nid);
+#endif
         if (digest)
         {
             /* We cast the const away so we can keep the function prototype
@@ -449,7 +473,7 @@ 
             print_digest((EVP_MD *)digest, NULL);
         }
     }
-#endif
+#endif /* if OPENSSL_VERSION_NUMBER >= 0x30000000L */
     printf("\n");
 }