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Blame 0416-Ticket-48987-Heap-use-after-free-in-dblayer_close_in.patch

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From aaae3f590d92cbdb301a82e248bda2248bc18bb6 Mon Sep 17 00:00:00 2001
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From: Noriko Hosoi <nhosoi@redhat.com>
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Date: Wed, 28 Sep 2016 15:28:28 -0700
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Subject: [PATCH 416/425] Ticket #48987 - Heap use after free in
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 dblayer_close_indexes
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Description: Once an attribute info is deleted, its backpointer
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dblayer_handle_ai_backpointer in the dblayer handle needs to be
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set to NULL not to access the address again. We also need to set
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this to null from within the dblayer_close_indexes because there
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is no guarantee on the order that we free the handle or the
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attrinfo.
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https://fedorahosted.org/389/ticket/48987
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Author: nhosoi, wibrown
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Review: nhosoi (Thanks!)
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(cherry picked from commit 99176404bfe76ee9fcf48b8b28750ec3979ec020)
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(cherry picked from commit f4b2a54d45606d61828d37b2a901f799a2de5f7b)
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---
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 ldap/servers/slapd/back-ldbm/dblayer.c   | 8 +++++++-
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 ldap/servers/slapd/back-ldbm/ldbm_attr.c | 4 ++++
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 2 files changed, 11 insertions(+), 1 deletion(-)
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diff --git a/ldap/servers/slapd/back-ldbm/dblayer.c b/ldap/servers/slapd/back-ldbm/dblayer.c
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index a08913b..fed5548 100644
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--- a/ldap/servers/slapd/back-ldbm/dblayer.c
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+++ b/ldap/servers/slapd/back-ldbm/dblayer.c
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@@ -2635,7 +2635,13 @@ int dblayer_close_indexes(backend *be)
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         pDB = handle->dblayer_dbp;
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         return_value |= pDB->close(pDB,0);
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         next = handle->dblayer_handle_next;
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-        *((dblayer_handle **)handle->dblayer_handle_ai_backpointer) = NULL;
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+        /* If the backpointer is still valid, NULL the attrinfos ref to us
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+         * This is important as there is no ordering guarantee between if the
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+         * handle or the attrinfo is freed first!
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+         */
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+        if (handle->dblayer_handle_ai_backpointer) {
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+            *((dblayer_handle **)handle->dblayer_handle_ai_backpointer) = NULL;
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+        }
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         slapi_ch_free((void**)&handle);
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     }
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diff --git a/ldap/servers/slapd/back-ldbm/ldbm_attr.c b/ldap/servers/slapd/back-ldbm/ldbm_attr.c
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index db087fe..862dcd1 100644
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--- a/ldap/servers/slapd/back-ldbm/ldbm_attr.c
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+++ b/ldap/servers/slapd/back-ldbm/ldbm_attr.c
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@@ -88,6 +88,10 @@ attrinfo_delete(struct attrinfo **pp)
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         slapi_ch_free((void**)&((*pp)->ai_attrcrypt));
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         attr_done(&((*pp)->ai_sattr));
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         attrinfo_delete_idlistinfo(&(*pp)->ai_idlistinfo);
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+        if ((*pp)->ai_dblayer) {
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+            /* attriinfo is deleted.  Cleaning up the backpointer at the same time. */
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+            ((dblayer_handle *)((*pp)->ai_dblayer))->dblayer_handle_ai_backpointer = NULL;
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+        }
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         slapi_ch_free((void**)pp);
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         *pp= NULL;
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     }
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-- 
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2.9.3
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