[
https://issues.apache.org/jira/browse/ZOOKEEPER-2890?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16153522#comment-16153522
]
Alexander A. Strelets commented on ZOOKEEPER-2890:
--------------------------------------------------
Also I have briefly verified the remaining cases in the
_deserialize_response()_.
As soon as all of them except _case COMPLETION_VOID_ and the mentioned _case
COMPLETION_STRING_ are not used for _multi_ response, there is no problem with
them.
However, if some of them are included into _multi_ response in further
releases, they also must be patched in the same way.
Here is the brief:
case COMPLETION_DATA: // get response
deserialize_Buffer(in, "data", &v->data) may left v->data uninitialized
... then deallocate_Buffer(&v->data) will free by uninitialized v->data
case COMPLETION_STRINGLIST: // get_children response
deserialize_String_vector(in, "children", &v->children) calls
start_vector(in, tag, &v->count) which may left v->children.count uninitialized
... then deserialize_String_vector() calls calloc(v->count, sizeof(*v->data))
which may face insufficient memory if v->count is a big number
... or at least lead to significant delay in executing the further
for(i=0;i<v->count;i++)
case COMPLETION_STRINGLIST_STAT: // get_children2 response
the same as the above case
case COMPLETION_STRING: // create response
described in the main part of the ticket
deserialize_String(in, "path", &v->path) may left v->path uninitialized
... then deallocate_String(&v->path) will free by uninitialized v->data
case COMPLETION_ACLLIST: // get_acl response
deserialize_ACL_vector(in, "acl", &v->acl) calls start_vector(in, tag,
&v->count) which may left v->acl.count uninitialized
... then deserialize_ACL_vector() calls calloc(v->count, sizeof(*v->data))
which may face insufficient memory if v->count is a big number
... or at least lead to significant delay in executing the further
for(i=0;i<v->count;i++)
On the other hand:
case COMPLETION_STAT -- looks safe as soon as _free()_ is not called for the
_struct Stat_.
> Local automatic variable is left uninitialized and then freed.
> --------------------------------------------------------------
>
> Key: ZOOKEEPER-2890
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2890
> Project: ZooKeeper
> Issue Type: Bug
> Components: c client
> Affects Versions: 3.4.10
> Environment: Linux ubuntu 4.4.0-87-generic
> gcc (Ubuntu 5.4.0-6ubuntu1~16.04.4) 5.4.0 20160609
> https://github.com/apache/zookeeper.git
> branch-3.4
> Reporter: Alexander A. Strelets
> Priority: Critical
> Labels: easyfix
> Fix For: 3.4.10
>
>
> Function *_deserialize_response()_*, in _case COMPLETION_STRING_, uses local
> automatic variable *_struct CreateResponse res_* which is +left
> uninitialized+ and passed to the function _deserialize_GetACLResponse()_ and
> then to _deallocate_GetACLResponse()_.
> The _deserialize_ function, which is called the first, is expected to assign
> the _res_ variable with a value from the parsed _struct iarchive *ia_. But,
> if _ia_ contains for example insufficient amount of bytes the
> _deserialize_String()_ function refuses of assigning a value to _res_, and
> _res_ stays uninitialized (the true case is described below). Then, the
> _deallocate_ function calls _deallocate_String()_ passing uninitialized _res_
> with arguments. If incidentally the memory region in the program stack under
> the _res_ was not equal to NULL, the last call +leads to _free()_ by invalid
> address+.
> The true case: this happens when an active _multi_ request with _create_
> sub-request is completed on call to _zookeeper_close()_ with the so called
> "Fake response" which is fabricated by the function _free_completions()_.
> Such response includes only the header but +zero bytes for the body+. The
> significant condition is that the _create_ request is not a stand-alone one,
> but namely a sub-request within the _multi_ request. In this case the
> _deserialize_response()_ is called recursively (for each sub-request), and
> when it is called for the _create_ subrequest (from the nested
> _deserialize_multi()_) the _failed_ parameter is assigned with false (0), so
> the _if (failed)_ condition branches to the _else_ part. Note that in the
> stand-alone create-request case this does not occur.
> *I suspect this may happen not only due to call to _zookeeper_close()_ but on
> reception of a true multi-response from the server* containing insufficient
> number of bytes (I'm not sure if it can be a proper response from the server
> with an error overall status and empty or insufficient payload).
--
This message was sent by Atlassian JIRA
(v6.4.14#64029)
