From 63bcf189be73a9cc1264059bed6f57974be74a83 Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Tue, 13 Dec 2022 14:54:55 +0000
Subject: [PATCH 04/18] Avoid dangling ptrs in header and data params for
PEM_read_bio_ex
In the event of a failure in PEM_read_bio_ex() we free the buffers we
allocated for the header and data buffers. However we were not clearing
the ptrs stored in *header and *data. Since, on success, the caller is
responsible for freeing these ptrs this can potentially lead to a double
free if the caller frees them even on failure.
Thanks to Dawei Wang for reporting this issue.
Based on a proposed patch by Kurt Roeckx.
CVE-2022-4450
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Hugo Landau <hlandau@openssl.org>
---
crypto/pem/pem_lib.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/crypto/pem/pem_lib.c b/crypto/pem/pem_lib.c
index f9ff80162a..85c47fb627 100644
--- a/crypto/pem/pem_lib.c
+++ b/crypto/pem/pem_lib.c
@@ -989,7 +989,9 @@ int PEM_read_bio_ex(BIO *bp, char **name_out, char **header,
out_free:
pem_free(*header, flags, 0);
+ *header = NULL;
pem_free(*data, flags, 0);
+ *data = NULL;
end:
EVP_ENCODE_CTX_free(ctx);
pem_free(name, flags, 0);
--
2.39.1
From cbafa34b5a057794c5c08cd4657038e1f643c1ac Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Tue, 13 Dec 2022 15:02:26 +0000
Subject: [PATCH 05/18] Add a test for CVE-2022-4450
Call PEM_read_bio_ex() and expect a failure. There should be no dangling
ptrs and therefore there should be no double free if we free the ptrs on
error.
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Hugo Landau <hlandau@openssl.org>
---
test/pemtest.c | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/test/pemtest.c b/test/pemtest.c
index a8d2d49bb5..a5d28cb256 100644
--- a/test/pemtest.c
+++ b/test/pemtest.c
@@ -96,6 +96,35 @@ static int test_cert_key_cert(void)
return 1;
}
+static int test_empty_payload(void)
+{
+ BIO *b;
+ static char *emptypay =
+ "-----BEGIN CERTIFICATE-----\n"
+ "-\n" /* Base64 EOF character */
+ "-----END CERTIFICATE-----";
+ char *name = NULL, *header = NULL;
+ unsigned char *data = NULL;
+ long len;
+ int ret = 0;
+
+ b = BIO_new_mem_buf(emptypay, strlen(emptypay));
+ if (!TEST_ptr(b))
+ return 0;
+
+ /* Expected to fail because the payload is empty */
+ if (!TEST_false(PEM_read_bio_ex(b, &name, &header, &data, &len, 0)))
+ goto err;
+
+ ret = 1;
+ err:
+ OPENSSL_free(name);
+ OPENSSL_free(header);
+ OPENSSL_free(data);
+ BIO_free(b);
+ return ret;
+}
+
int setup_tests(void)
{
if (!TEST_ptr(pemfile = test_get_argument(0)))
@@ -103,5 +132,6 @@ int setup_tests(void)
ADD_ALL_TESTS(test_b64, OSSL_NELEM(b64_pem_data));
ADD_TEST(test_invalid);
ADD_TEST(test_cert_key_cert);
+ ADD_TEST(test_empty_payload);
return 1;
}
--
2.39.1