On Tue, Mar 19, 2019 at 05:09:33PM +0100, Michal Privoznik wrote:
On 3/19/19 4:53 PM, Ján Tomko wrote:On Mon, Mar 18, 2019 at 05:27:39PM +0100, Michal Privoznik wrote:https://bugzilla.redhat.com/show_bug.cgi?id=1686927 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. Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx> --- src/conf/virnwfilterbindingobjlist.c | 11 ++++++----- src/conf/virnwfilterbindingobjlist.h | 2 +- src/nwfilter/nwfilter_driver.c | 5 ++--- 3 files changed, 9 insertions(+), 9 deletions(-) diff --git a/src/conf/virnwfilterbindingobjlist.c b/src/conf/virnwfilterbindingobjlist.c index 06ccbf53af..87189da642 100644 --- a/src/conf/virnwfilterbindingobjlist.c +++ b/src/conf/virnwfilterbindingobjlist.c @@ -164,23 +164,24 @@ virNWFilterBindingObjListAddObjLocked(virNWFilterBindingObjListPtr bindings, */ static virNWFilterBindingObjPtr virNWFilterBindingObjListAddLocked(virNWFilterBindingObjListPtr bindings, - virNWFilterBindingDefPtr def) + virNWFilterBindingDefPtr *def)Rather than adding another return value to the whole chain,{ virNWFilterBindingObjPtr binding; /* See if a binding with matching portdev already exists */ if ((binding = virNWFilterBindingObjListFindByPortDevLocked( - bindings, def->portdevname))) { + bindings, (*def)->portdevname))) { virReportError(VIR_ERR_OPERATION_FAILED, _("binding '%s' already exists"), - def->portdevname); + (*def)->portdevname); goto error; } if (!(binding = virNWFilterBindingObjNew())) goto error; - virNWFilterBindingObjSetDef(binding, def); + virNWFilterBindingObjSetDef(binding, *def); + *def = NULL; if (virNWFilterBindingObjListAddObjLocked(bindings, binding) < 0)I'd simply set binding->def = NULL; here, to match what virDomainObjListAddLocked does.How can this work? binding's structure is internal so the only way to do
Hmm, not good. My other suggestions would be: * create an ugly virNWFilterBindingObjResetDef API * make another copy of the definition and make virNWFilterBindingObjListAdd always consume it
diff --git a/src/nwfilter/nwfilter_driver.c b/src/nwfilter/nwfilter_driver.c
index fdfc6f48fa..8c2e987b5d 100644
--- a/src/nwfilter/nwfilter_driver.c
+++ b/src/nwfilter/nwfilter_driver.c
@@ -759,7 +759,7 @@ nwfilterBindingCreateXML(virConnectPtr conn,
goto cleanup;
obj = virNWFilterBindingObjListAdd(driver->bindings,
- def);
+ &def);
if (!obj)
goto cleanup;
As-is, def would be NULL even on success and dereferenced on the next line. Jano
@@ -775,8 +775,7 @@ nwfilterBindingCreateXML(virConnectPtr conn,
virNWFilterBindingObjSave(obj, driver->bindingDir);
cleanup:
- if (!obj)
- virNWFilterBindingDefFree(def);
+ virNWFilterBindingDefFree(def);
virNWFilterBindingObjEndAPI(&obj);
return ret;
this would be by calling virNWFilterBindingObjSetDef(binding, NULL) which would free @def immediatelly and thus we wouldn't avoid double free. Can you shed more light what you have on mind please? Thanks, Michal -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
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