From: Ralph Boehme <slow@samba.org>
Date: Fri, 20 Aug 2021 13:04:49 +0000 (+0200)
Subject: CVE-2020-25717 winbind: ensure wb_parent_idmap_setup_send() gets called in winbindd_a... 
X-Git-Tag: samba-4.13.14~237
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4a39d8a1610b635760ac182be894d206eb0a1ee7;p=thirdparty%2Fsamba.git

CVE-2020-25717 winbind: ensure wb_parent_idmap_setup_send() gets called in winbindd_allocate_uid_send()

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14804
RN: winbindd can crash because idmap child state is not fully initialized

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Volker Lendecke <vl@samba.org>

Autobuild-User(master): Volker Lendecke <vl@samba.org>
Autobuild-Date(master): Thu Sep  2 15:20:06 UTC 2021 on sn-devel-184

(cherry picked from commit d0f6d54354b02f5591706814fbd1e4844788fdfa)

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14556

(cherry picked from commit 446f89510f2e55a551e2975a6cbf01c6a023ba0c)
---

diff --git a/source3/winbindd/winbindd_allocate_uid.c b/source3/winbindd/winbindd_allocate_uid.c
index 69ce61c872e..64711f1b661 100644
--- a/source3/winbindd/winbindd_allocate_uid.c
+++ b/source3/winbindd/winbindd_allocate_uid.c
@@ -22,9 +22,11 @@
 #include "librpc/gen_ndr/ndr_winbind_c.h"
 
 struct winbindd_allocate_uid_state {
+	struct tevent_context *ev;
 	uint64_t uid;
 };
 
+static void winbindd_allocate_uid_initialized(struct tevent_req *subreq);
 static void winbindd_allocate_uid_done(struct tevent_req *subreq);
 
 struct tevent_req *winbindd_allocate_uid_send(TALLOC_CTX *mem_ctx,
@@ -34,25 +36,57 @@ struct tevent_req *winbindd_allocate_uid_send(TALLOC_CTX *mem_ctx,
 {
 	struct tevent_req *req, *subreq;
 	struct winbindd_allocate_uid_state *state;
-	struct dcerpc_binding_handle *child_binding_handle = NULL;
 
 	req = tevent_req_create(mem_ctx, &state,
 				struct winbindd_allocate_uid_state);
 	if (req == NULL) {
 		return NULL;
 	}
+        state->ev = ev;
 
 	DEBUG(3, ("allocate_uid\n"));
 
-	child_binding_handle = idmap_child_handle();
+	subreq = wb_parent_idmap_setup_send(state, ev);
+	if (tevent_req_nomem(subreq, req)) {
+		return tevent_req_post(req, ev);
+	}
+	tevent_req_set_callback(subreq, winbindd_allocate_uid_initialized, req);
+	return req;
+}
+
+static void winbindd_allocate_uid_initialized(struct tevent_req *subreq)
+{
+	struct tevent_req *req = tevent_req_callback_data(
+		subreq, struct tevent_req);
+	struct dcerpc_binding_handle *child_binding_handle = NULL;
+	struct winbindd_allocate_uid_state *state = tevent_req_data(
+		req, struct winbindd_allocate_uid_state);
+	const struct wb_parent_idmap_config *cfg = NULL;
+	NTSTATUS status;
+
+	status = wb_parent_idmap_setup_recv(subreq, &cfg);
+	TALLOC_FREE(subreq);
+	if (tevent_req_nterror(req, status)) {
+		return;
+	}
+	if (cfg->num_doms == 0) {
+		/*
+		 * idmap_tdb also returns UNSUCCESSFUL if a range is full
+		 */
+		tevent_req_nterror(req, NT_STATUS_UNSUCCESSFUL);
+		return;
+	}
+
+        child_binding_handle = idmap_child_handle();
 
-	subreq = dcerpc_wbint_AllocateUid_send(state, ev, child_binding_handle,
+        subreq = dcerpc_wbint_AllocateUid_send(state,
+					       state->ev,
+                                               child_binding_handle,
 					       &state->uid);
 	if (tevent_req_nomem(subreq, req)) {
-		return tevent_req_post(req, ev);
+		return;
 	}
 	tevent_req_set_callback(subreq, winbindd_allocate_uid_done, req);
-	return req;
 }
 
 static void winbindd_allocate_uid_done(struct tevent_req *subreq)