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