From 3bdc110e167d7e0f20022dea48ec51b1f46369cb Mon Sep 17 00:00:00 2001 From: Gary Lockyer Date: Wed, 13 May 2020 10:56:56 +1200 Subject: [PATCH 10/11] CVE-2020-10730: lib ldb: Check if ldb_lock_backend_callback called twice Prevent use after free issues if ldb_lock_backend_callback is called twice, usually due to ldb_module_done being called twice. This can happen if a module ignores the return value from function a function that calls ldb_module_done as part of it's error handling. BUG: https://bugzilla.samba.org/show_bug.cgi?id=14364 Signed-off-by: Gary Lockyer Reviewed-by: Andrew Bartlett --- lib/ldb/common/ldb.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/lib/ldb/common/ldb.c b/lib/ldb/common/ldb.c index 44a487ba987..090d41dde69 100644 --- a/lib/ldb/common/ldb.c +++ b/lib/ldb/common/ldb.c @@ -1009,6 +1009,13 @@ static int ldb_lock_backend_callback(struct ldb_request *req, struct ldb_db_lock_context *lock_context; int ret; + if (req->context == NULL) { + /* + * The usual way to get here is to ignore the return codes + * and continuing processing after an error. + */ + abort(); + } lock_context = talloc_get_type(req->context, struct ldb_db_lock_context); @@ -1023,7 +1030,7 @@ static int ldb_lock_backend_callback(struct ldb_request *req, * If this is a LDB_REPLY_DONE or an error, unlock the * DB by calling the destructor on this context */ - talloc_free(lock_context); + TALLOC_FREE(req->context); return ret; } -- 2.17.1