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Mon, 16 Nov 2020 15:22:58 +0100 (CET) From: Markus Armbruster To: Eric Blake Subject: Re: [PATCH v2 1/7 for-5.2?] net: Fix memory leak on error References: <20201113011340.463563-1-eblake@redhat.com> <20201113011340.463563-2-eblake@redhat.com> Date: Mon, 16 Nov 2020 15:22:58 +0100 In-Reply-To: <20201113011340.463563-2-eblake@redhat.com> (Eric Blake's message of "Thu, 12 Nov 2020 19:13:34 -0600") Message-ID: <87pn4didod.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain Received-SPF: pass client-ip=63.128.21.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/11/16 04:46:27 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jason Wang , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Eric Blake writes: > If qmp_query_rx_filter() encounters an error on a second iteration, it > leaks the memory from the first. > > Fixes: 9083da1d4c > Signed-off-by: Eric Blake > --- > net/net.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/net/net.c b/net/net.c > index 794c652282cb..eb65e110871a 100644 > --- a/net/net.c > +++ b/net/net.c > @@ -1213,6 +1213,7 @@ RxFilterInfoList *qmp_query_rx_filter(bool has_name, const char *name, NetClientState *nc; RxFilterInfoList *filter_list = NULL, *last_entry = NULL; QTAILQ_FOREACH(nc, &net_clients, next) { RxFilterInfoList *entry; RxFilterInfo *info; if (has_name && strcmp(nc->name, name) != 0) { continue; } If @has_name and we get here more than once, then multiple @net_clients have the same name. How can that be? We are not supposed to return multiple replies with the same @name, are we? /* only query rx-filter information of NIC */ > if (nc->info->type != NET_CLIENT_DRIVER_NIC) { > if (has_name) { > error_setg(errp, "net client(%s) isn't a NIC", name); > + qapi_free_RxFilterInfoList(filter_list); Unless multiple @net_clients are named @name, @filter_list is null, isn't it? > return NULL; > } > continue; } /* only query information on queue 0 since the info is per nic, * not per queue */ if (nc->queue_index != 0) continue; if (nc->info->query_rx_filter) { info = nc->info->query_rx_filter(nc); entry = g_malloc0(sizeof(*entry)); entry->value = info; if (!filter_list) { filter_list = entry; >From now on, we must either return or free @filter_list. } else { last_entry->next = entry; } last_entry = entry; > @@ -1238,6 +1239,7 @@ RxFilterInfoList *qmp_query_rx_filter(bool has_name, const char *name, > } else if (has_name) { > error_setg(errp, "net client(%s) doesn't support" > " rx-filter querying", name); > + qapi_free_RxFilterInfoList(filter_list); Unless multiple @net_clients are named @name, @filter_list is null, isn't it? > return NULL; > } if (has_name) { break; } } I dislike this loop. if (filter_list == NULL && has_name) { error_setg(errp, "invalid net client name: %s", name); } return filter_list; I should've strangled the optional @name parameter in the crib.