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bh=NpYemzGwoC94cXQf0d03qM7bmu2KRMbztfKsbPHaFKY=; b=Ho5nCqF/jDiSreOckmKEdhuoMXp81k0rcmqtfLZ783Utla7eXZAEi4EoajYX8H7dimJbDF HDiqiOXkaAeAaUX9hNmW+fyCNGPT+t4m6TyFTJKa/SPsI0p1TaqhC2fHeEuiy3YelxmHzf ELOCczHpKKD9yd7IWF/wkMkLih7ndc0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-500-akVyDB_UNpWqPzndP55gCQ-1; Tue, 15 Dec 2020 16:23:36 -0500 X-MC-Unique: akVyDB_UNpWqPzndP55gCQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 82A9D1084C9C; Tue, 15 Dec 2020 21:23:07 +0000 (UTC) Received: from localhost (ovpn-115-226.rdu2.redhat.com [10.10.115.226]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1CBA560C0F; Tue, 15 Dec 2020 21:23:06 +0000 (UTC) Date: Tue, 15 Dec 2020 16:23:05 -0500 From: Eduardo Habkost To: Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Subject: Re: [PULL 1/2] test-char: abort on serial test error Message-ID: <20201215212305.GC3140057@habkost.net> References: <20200728143108.2192896-1-marcandre.lureau@redhat.com> <20200728143108.2192896-2-marcandre.lureau@redhat.com> <20201215192922.GB3140057@habkost.net> MIME-Version: 1.0 In-Reply-To: <20201215192922.GB3140057@habkost.net> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=ehabkost@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=ehabkost@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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_H4=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: peter.maydell@linaro.org, =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , qemu-devel@nongnu.org, Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Dec 15, 2020 at 02:29:22PM -0500, Eduardo Habkost wrote: > On Sun, Dec 13, 2020 at 11:51:05PM +0100, Philippe Mathieu-Daudé wrote: > > On 7/28/20 4:31 PM, Marc-André Lureau wrote: > > > We are having issues debugging and bisecting this issue that happen > > > mostly on patchew. Let's make it abort where it failed to gather some > > > new informations. > > > > "good" news, this started to fail on Gitlab (centos7): > > > > Running test test-char > > Unexpected error in object_property_try_add() at ../qom/object.c:1220: > > attempt to add duplicate property 'serial-id' to object (type 'container') > > ERROR test-char - too few tests run (expected 38, got 9) > > make: *** [run-test-86] Error 1 > > > > https://gitlab.com/philmd/qemu/-/jobs/908114388 > > https://gitlab.com/philmd/qemu/-/jobs/908114389 > > https://gitlab.com/philmd/qemu/-/jobs/908114390 > > Do we have any clue what could be causing this? After looking at > the code, it smells like memory corruption. > > At first, I thought it could be due to the multi-threaded test > cases, but the test binary seems to be crashing before the > multi-threaded test cases have an opportunity to run. I think I know what's happening: - char_file_test_internal() creates chr using qemu_chardev_new(). - qemu_chardev_new() automatically assigns ID, adds chardev to the QOM tree. - char_file_test_internal() does _not_ own the reference to the created object. - char_file_test_internal() incorrectly calls object_unref(). - object is freed but, but /containers now has a dangling pointer. - char_serial_test() creates a chardev with ID "serial-id", and it ends up being allocated at the same address as the old object. - char_serial_test() correctly calls object_unparent(). - object_property_del_child() looks for the right child property in the hashtable, finds the dangling pointer with the same address, removes the wrong property, leaves a dangling "serial-id" property. - New object is created by char_serial_test() with ID "serial-id". - object_property_try_add_child() will fail because of the dangling "serial-id" property. The bug in char_file_test_internal() was detected using the following patch. I believe the bug was introduced by commit 1e419ee68fa5 ("chardev: generate an internal id when none given") because it changed the reference ownership semantics of qemu_chardev_new(NULL, ...). Signed-off-by: Eduardo Habkost --- diff --git a/qom/object.c b/qom/object.c index f2ae6e6b2a..5cfed6d7c6 100644 --- a/qom/object.c +++ b/qom/object.c @@ -685,6 +685,7 @@ static void object_finalize(void *data) object_deinit(obj, ti); g_assert(obj->ref == 0); + g_assert(obj->parent == NULL); if (obj->free) { obj->free(obj); } -- Eduardo