From 48289dddc0f4398036071c132f96644e3c3e03c4 Mon Sep 17 00:00:00 2001
Message-Id: <48289dddc0f4398036071c132f96644e3c3e03c4@dist-git>
From: Michal Privoznik <mprivozn@redhat.com>
Date: Tue, 23 Apr 2019 10:06:17 +0200
Subject: [PATCH] virnwfilterbindingobj: Introduce and use
 virNWFilterBindingObjStealDef
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RHEL-7.7: https://bugzilla.redhat.com/show_bug.cgi?id=1686927
RHEL-7.6.z: https://bugzilla.redhat.com/show_bug.cgi?id=1702173

When trying to create a nwfilter binding via
nwfilterBindingCreateXML() we may encounter a crash. The sequence
of functions called is as follows:

1) nwfilterBindingCreateXML() parses the XML and calls
virNWFilterBindingObjListAdd() which calls
virNWFilterBindingObjListAddLocked()

2) Here, @binding is not found because binding->remove is set.

3) Therefore, controls continue with creating new @binding,
setting its def to the one from 1) and adding it to the hash
table.

4) This fails, because the binding is still in the hash table
(duplicate key is detected).

5) The control jumps to 'error' label where
virNWFilterBindingObjEndAPI() is called which frees the binding
definition passed.

6) Error is propagated to the caller, which calls
virNWFilterBindingDefFree() over the definition again.

The solution is to unset binding->def in case of failure so it's
not freed in step 5).

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
(cherry picked from commit 8c08a99745ddac9f4055c008e82e68a27ed5093d)
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Message-Id: <a5c2feed107e958bb6a84f7e993cc9feac58c4a2.1556006751.git.mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
---
 src/conf/virnwfilterbindingobj.c     | 10 ++++++++++
 src/conf/virnwfilterbindingobj.h     |  3 +++
 src/conf/virnwfilterbindingobjlist.c |  4 ++++
 src/libvirt_private.syms             |  1 +
 4 files changed, 18 insertions(+)

diff --git a/src/conf/virnwfilterbindingobj.c b/src/conf/virnwfilterbindingobj.c
index d145fe3223..291ba9a5f8 100644
--- a/src/conf/virnwfilterbindingobj.c
+++ b/src/conf/virnwfilterbindingobj.c
@@ -88,6 +88,16 @@ virNWFilterBindingObjSetDef(virNWFilterBindingObjPtr obj,
 }
 
 
+virNWFilterBindingDefPtr
+virNWFilterBindingObjStealDef(virNWFilterBindingObjPtr obj)
+{
+    virNWFilterBindingDefPtr def;
+
+    VIR_STEAL_PTR(def, obj->def);
+    return def;
+}
+
+
 bool
 virNWFilterBindingObjGetRemoving(virNWFilterBindingObjPtr obj)
 {
diff --git a/src/conf/virnwfilterbindingobj.h b/src/conf/virnwfilterbindingobj.h
index 21ae85b064..e8f94aa1ef 100644
--- a/src/conf/virnwfilterbindingobj.h
+++ b/src/conf/virnwfilterbindingobj.h
@@ -38,6 +38,9 @@ void
 virNWFilterBindingObjSetDef(virNWFilterBindingObjPtr obj,
                             virNWFilterBindingDefPtr def);
 
+virNWFilterBindingDefPtr
+virNWFilterBindingObjStealDef(virNWFilterBindingObjPtr obj);
+
 bool
 virNWFilterBindingObjGetRemoving(virNWFilterBindingObjPtr obj);
 
diff --git a/src/conf/virnwfilterbindingobjlist.c b/src/conf/virnwfilterbindingobjlist.c
index 7ce59f7c6e..d0301e7e28 100644
--- a/src/conf/virnwfilterbindingobjlist.c
+++ b/src/conf/virnwfilterbindingobjlist.c
@@ -169,6 +169,7 @@ virNWFilterBindingObjListAddLocked(virNWFilterBindingObjListPtr bindings,
                                    virNWFilterBindingDefPtr def)
 {
     virNWFilterBindingObjPtr binding;
+    bool stealDef = false;
 
     /* See if a binding with matching portdev already exists */
     if ((binding = virNWFilterBindingObjListFindByPortDevLocked(
@@ -183,6 +184,7 @@ virNWFilterBindingObjListAddLocked(virNWFilterBindingObjListPtr bindings,
         goto error;
 
     virNWFilterBindingObjSetDef(binding, def);
+    stealDef = true;
 
     if (virNWFilterBindingObjListAddObjLocked(bindings, binding) < 0)
         goto error;
@@ -190,6 +192,8 @@ virNWFilterBindingObjListAddLocked(virNWFilterBindingObjListPtr bindings,
     return binding;
 
  error:
+    if (stealDef)
+        virNWFilterBindingObjStealDef(binding);
     virNWFilterBindingObjEndAPI(&binding);
     return NULL;
 }
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 636891eabd..3325b90535 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1065,6 +1065,7 @@ virNWFilterBindingObjParseFile;
 virNWFilterBindingObjSave;
 virNWFilterBindingObjSetDef;
 virNWFilterBindingObjSetRemoving;
+virNWFilterBindingObjStealDef;
 
 
 # conf/virnwfilterbindingobjlist.h
-- 
2.21.0