Don't hold a lock when calling a callback in ossl_namemap_doall_names

We don't want to hold a read lock when calling a user supplied callback.
That callback could do anything so the risk of a deadlock is high.
Instead we collect all the names first inside the read lock, and then
subsequently call the user callback outside the read lock.

Fixes #14225

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/14250)

1 files changed, 6 insertions, 4 deletions

diff --git a/crypto/evp/mac_lib.c b/crypto/evp/mac_lib.c
index c5c12598d3..de4d3623ff 100644
--- a/crypto/evp/mac_lib.c
+++ b/crypto/evp/mac_lib.c
@@ -174,10 +174,12 @@ int EVP_MAC_is_a(const EVP_MAC *mac, const char *name)
     return evp_is_a(mac->prov, mac->name_id, NULL, name);
 }
 
-void EVP_MAC_names_do_all(const EVP_MAC *mac,
-                          void (*fn)(const char *name, void *data),
-                          void *data)
+int EVP_MAC_names_do_all(const EVP_MAC *mac,
+                         void (*fn)(const char *name, void *data),
+                         void *data)
 {
     if (mac->prov != NULL)
-        evp_names_do_all(mac->prov, mac->name_id, fn, data);
+        return evp_names_do_all(mac->prov, mac->name_id, fn, data);
+
+    return 1;
 }