Re: Segfault while running SSL Labs CurveBall test

Hi,

On Thu, Jan 15, 2026 at 09:44:50PM +0000, [email protected] wrote:
>Hi,
>
>I was running some tests from ssllabs.com and ran into a segfault.
>
>I used the "CurveBall" manual test link from this page:
>https://clienttest.ssllabs.com:8443/ssltest/viewMyClient.html
>
>Which points to: https://www.ssllabs.com:10446/
>
>Nav_open_url: new url='https://www.ssllabs.com:10446/'
>Connecting to 69.67.183.100:10446
>www.ssllabs.com:10446: TLSv1.2, cipher ECDHE-ECDSA-AES256-GCM-SHA384
>ecdsa-with-SHA256 384-bit EC: /C=US/ST=California/L=Foster City/O=Qualys, Inc./OU=SSLLabs CurveBall Leaf/CN=www.ssllabs.com
>ecdsa-with-SHA256
>Program received signal SIGSEGV, Segmentation fault.
>_lcry_EVP_PKEY_id (pkey=0x0) at /usr/src/lib/libcrypto/evp/p_lib.c:793
>793                return pkey->type;
>(gdb) bt
>#0  _lcry_EVP_PKEY_id (pkey=0x0) at /usr/src/lib/libcrypto/evp/p_lib.c:793
>#1  0x000001f9ee7da2b0 in Tls_check_cert_strength (ssl=<optimized out>,
>    srv=<optimized out>, choice=0x6faff21f66f8) at tls_openssl.c:526
>#2  0x000001f9ee7d8fd3 in Tls_examine_certificate (ssl=0x1fca8ddac80, srv=0x1fc1b4056a0)
>    at tls_openssl.c:865
>#3  Tls_connect (fd=7, connkey=4) at tls_openssl.c:1208
>#4  0x000001fce9a7a7f0 in fl_wait(double) () from /usr/local/lib/libfltk.so.9.0
>#5  0x000001fce9a0777f in Fl::wait(double) () from /usr/local/lib/libfltk.so.9.0
>#6  0x000001fce9a079a1 in Fl::wait() () from /usr/local/lib/libfltk.so.9.0
>#7  0x000001f9ee77e774 in main (argc=1, argv=0x6faff21f6a48) at dillo.cc:621
>
>When I try to open it with curl, this is the result:
>curl: (35) TLS connect error: error:10FFF010:elliptic curve routines:CRYPTO_internal:EC lib
>
>This is on OpenBSD, using LibreSSL.
>
>I did a curl test on a Linux box and didn't get that error, so it may
>be LibreSSL specific.

Thanks, I can reproduce it on Linux with LibreSSL 4.2.1 and ASan 
enabled:

==1123582==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x7f31c4d0b3a4 bp 0x7ffc3dc12070 sp 0x7ffc3dc10eb8 T0)
==1123582==The signal is caused by a READ memory access.
==1123582==Hint: address points to the zero page.
     #0 0x7f31c4d0b3a4 in EVP_PKEY_id (/usr/lib/libressl/libcrypto.so.57+0xae3a4) (BuildId: 15f17022dc7dbd5298bf906f2ef4e53d12c52015)
     #1 0x55c7110c71cf in Tls_check_cert_strength ../../../src/IO/tls_openssl.c:525
     #2 0x55c7110c87d1 in Tls_examine_certificate ../../../src/IO/tls_openssl.c:864
     #3 0x55c7110ca507 in Tls_connect ../../../src/IO/tls_openssl.c:1207
     #4 0x55c7110ca6e0 in Tls_connect_cb ../../../src/IO/tls_openssl.c:1239
     #5 0x7f31c4ab06ec in fl_wait(double) (/usr/lib/libfltk.so.1.3+0xa66ec) (BuildId: 35d154011fe6e73efbad51f873a8c4e488e91451)
     #6 0x7f31c4a4e0fd in Fl::wait(double) (/usr/lib/libfltk.so.1.3+0x440fd) (BuildId: 35d154011fe6e73efbad51f873a8c4e488e91451)
     #7 0x7f31c4a4e232 in Fl::wait() (/usr/lib/libfltk.so.1.3+0x44232) (BuildId: 35d154011fe6e73efbad51f873a8c4e488e91451)
     #8 0x55c710fd9009 in main ../../src/dillo.cc:621
     #9 0x7f31c4227634  (/usr/lib/libc.so.6+0x27634) (BuildId: 2f722da304c0a508c891285e6840199c35019c8d)
     #10 0x7f31c42276e8 in __libc_start_main (/usr/lib/libc.so.6+0x276e8) (BuildId: 2f722da304c0a508c891285e6840199c35019c8d)
     #11 0x55c710fd5f74 in _start (/home/ram/dev/dillo/git/build-asan/src/dillo+0x12f74) (BuildId: 850e3f88a121a05841fca5389243b0482d69b6b0)

This patch should get rid of the segfault, but I need to take a closer 
look and see if we are handling it well for LibreSSL, as they expose 
headers from version 2 from OpenSSL.

---8<---
diff --git a/src/IO/tls_openssl.c b/src/IO/tls_openssl.c
index 3345a0dc..d1df2315 100644
--- a/src/IO/tls_openssl.c
+++ b/src/IO/tls_openssl.c
@@ -471,14 +471,12 @@ static bool_t Tls_check_cert_strength(SSL *ssl, Server_t *srv, int *choice)
        char buf[buflen];
        int rc, i, n = sk_X509_num(sk);
        X509 *cert = NULL;
-      EVP_PKEY *public_key;
        int key_type, key_bits;
        const char *type_str;
        BIO *b;

        for (i = 0; i < n; i++) {
           cert = sk_X509_value(sk, i);
-         public_key = X509_get_pubkey(cert);

           /* We are trying to find a way to get the hash function used
            * with a certificate. This way, which is not very pleasant, puts
@@ -521,6 +519,10 @@ static bool_t Tls_check_cert_strength(SSL *ssl, Server_t *srv, int *choice)
           if (print_chain)
              MSG("%s ", buf);

+         EVP_PKEY *public_key = X509_get_pubkey(cert);
+         if (public_key == NULL)
+            continue;
+
  #if OPENSSL_VERSION_NUMBER < 0x30000000L
           key_type = EVP_PKEY_type(EVP_PKEY_id(public_key));
  #else
---8<---

Best,
Rodrigo.
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