Correct error code processing

Fix missing error codes set and invalid error code checks in OpenSSH. It
prevents memory exhaustion attack and a MITM attack when VerifyHostKeyDNS
is on (CVE-2025-26465).

Resolves: RHEL-78700

openssh-9.9p2-error_processing.patch

@@ -0,0 +1,69 @@
+diff --git a/krl.c b/krl.c
+index e2efdf06..0d0f6953 100644
+--- a/krl.c
++++ b/krl.c
+@@ -674,6 +674,7 @@ revoked_certs_generate(struct revoked_certs *rc, struct sshbuf *buf)
+ 			break;
+ 		case KRL_SECTION_CERT_SERIAL_BITMAP:
+ 			if (rs->lo - bitmap_start > INT_MAX) {
++				r = SSH_ERR_INVALID_FORMAT;
+ 				error_f("insane bitmap gap");
+ 				goto out;
+ 			}
+@@ -1059,6 +1060,7 @@ ssh_krl_from_blob(struct sshbuf *buf, struct ssh_krl **krlp)
+ 		goto out;
+ 
+ 	if ((krl = ssh_krl_init()) == NULL) {
++		r = SSH_ERR_ALLOC_FAIL;
+ 		error_f("alloc failed");
+ 		goto out;
+ 	}
+diff --git a/sshconnect2.c b/sshconnect2.c
+index a69c4da1..1ee6000a 100644
+--- a/sshconnect2.c
++++ b/sshconnect2.c
+@@ -99,7 +99,7 @@ verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh)
+ 	    options.required_rsa_size)) != 0)
+ 		fatal_r(r, "Bad server host key");
+ 	if (verify_host_key(xxx_host, xxx_hostaddr, hostkey,
+-	    xxx_conn_info) == -1)
++	    xxx_conn_info) != 0)
+ 		fatal("Host key verification failed.");
+ 	return 0;
+ }
+@@ -699,6 +699,7 @@ input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh)
+ 
+ 	if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) {
+ 		debug_f("server sent unknown pkalg %s", pkalg);
++		r = SSH_ERR_INVALID_FORMAT;
+ 		goto done;
+ 	}
+ 	if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
+@@ -709,6 +710,7 @@ input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh)
+ 		error("input_userauth_pk_ok: type mismatch "
+ 		    "for decoded key (received %d, expected %d)",
+ 		    key->type, pktype);
++		r = SSH_ERR_INVALID_FORMAT;
+ 		goto done;
+ 	}
+ 
+@@ -728,6 +730,7 @@ input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh)
+ 		    SSH_FP_DEFAULT);
+ 		error_f("server replied with unknown key: %s %s",
+ 		    sshkey_type(key), fp == NULL ? "<ERROR>" : fp);
++		r = SSH_ERR_INVALID_FORMAT;
+ 		goto done;
+ 	}
+ 	ident = format_identity(id);
+diff --git a/sshsig.c b/sshsig.c
+index 6e03c0b0..3da005d6 100644
+--- a/sshsig.c
++++ b/sshsig.c
+@@ -879,6 +879,7 @@ cert_filter_principals(const char *path, u_long linenum,
+ 	}
+ 	if ((principals = sshbuf_dup_string(nprincipals)) == NULL) {
+ 		error_f("buffer error");
++		r = SSH_ERR_ALLOC_FAIL;
+ 		goto out;
+ 	}
+ 	/* success */

openssh.spec

@@ -47,7 +47,7 @@
 
 # Do not forget to bump pam_ssh_agent_auth release if you rewind the main package release to 1
 %global openssh_ver 8.7p1
-%global openssh_rel 44
+%global openssh_rel 45
 %global pam_ssh_agent_ver 0.10.4
 %global pam_ssh_agent_rel 5
 
@@ -297,6 +297,9 @@ Patch1022: openssh-8.7p1-redhat-help.patch
 Patch1023: openssh-8.7p1-openssl-log.patch
 #upstream commit 52dfe3c72d98503d8b7c6f64fc7e19d685636c0b
 Patch1024: openssh-8.7p1-allow-duplicate-subsystem.patch
+# upstream 6ce00f0c2ecbb9f75023dbe627ee6460bcec78c2
+# upstream 0832aac79517611dd4de93ad0a83577994d9c907
+Patch1025: openssh-9.9p2-error_processing.patch
 
 License: BSD
 Requires: /sbin/nologin
@@ -526,6 +529,7 @@ popd
 %patch1022 -p1 -b .redhat-help
 %patch1023 -p1 -b .openssl-log
 %patch1024 -p1 -b .allow-dup-subsystem
+%patch1025 -p1 -b .errcode_set
 
 autoreconf
 pushd pam_ssh_agent_auth-pam_ssh_agent_auth-%{pam_ssh_agent_ver}
@@ -813,6 +817,12 @@ test -f %{sysconfig_anaconda} && \
 %endif
 
 %changelog
+* Tue Feb 18 2025 Dmitry Belyavskiy <dbelyavs@redhat.com> - 8.7p1-45
+- Fix missing error codes set and invalid error code checks in OpenSSH. It
+  prevents memory exhaustion attack and a MITM attack when VerifyHostKeyDNS
+  is on (CVE-2025-26465).
+  Resolves: RHEL-78700
+
 * Mon Oct 21 2024 Dmitry Belyavskiy <dbelyavs@redhat.com> - 8.7p1-44
 - Add extra help information on ssh early failure
   Resolves: RHEL-33809