From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43568) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dmN08-0000vI-LP for qemu-devel@nongnu.org; Mon, 28 Aug 2017 12:35:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dmN07-0005yD-HL for qemu-devel@nongnu.org; Mon, 28 Aug 2017 12:35:00 -0400 From: Igor Mammedov Date: Mon, 28 Aug 2017 18:34:45 +0200 Message-Id: <1503938085-169486-1-git-send-email-imammedo@redhat.com> Subject: [Qemu-devel] [PATCH for-2.11] ide: ahci: unparent children buses before freeing their memory List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: jsnow@redhat.com, qemu-block@nongnu.org, thuth@redhat.com, f4bug@amsat.org, mst@redhat.com Fixes read after freeing error reported https://lists.gnu.org/archive/html/qemu-devel/2017-08/msg04243.html Message-Id: <59a56959-ca12-ea75-33fa-ff07eba1b090@redhat.com> ich9-ahci device creates ide buses and attaches them as QOM children at realize time, however it forgets to properly clean them up at unrealize time and frees memory containing these children, with following call-chain: qdev_device_add() object_property_set_bool('realized', true) device_set_realized() ... pci_qdev_realize() -> pci_ich9_ahci_realize() -> ahci_realize() ... s->dev = g_new0(AHCIDevice, ports); ... AHCIDevice *ad = &s->dev[i]; ide_bus_new(&ad->port, sizeof(ad->port), qdev, i, 1); ^^^ creates bus in memory allocated by above gnew() and adds it as child propety to ahci device ... hotplug_handler_plug(); -> goto post_realize_fail; pci_qdev_unrealize() -> pci_ich9_uninit() -> ahci_uninit() ... g_free(s->dev); ^^^ free memory that holds children busses return with error from device_set_realized() As result later when qdev_device_add() tries to unparent ich9-ahci after failed device_set_realized(), object_unparent() -> object_property_del_child() iterates over existing QOM children including buses added by ide_bus_new() and tries to unparent them, which causes access to freed memory where they where located. Reported-by: Thomas Huth Signed-off-by: Igor Mammedov --- hw/ide/ahci.c | 1 + 1 file changed, 1 insertion(+) diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c index 406a1b5..ccbe091 100644 --- a/hw/ide/ahci.c +++ b/hw/ide/ahci.c @@ -1495,6 +1495,7 @@ void ahci_uninit(AHCIState *s) ide_exit(s); } + object_unparent(OBJECT(&ad->port)); } g_free(s->dev); -- 2.7.4