From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33080) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X9cDN-0001ta-Mg for qemu-devel@nongnu.org; Tue, 22 Jul 2014 11:42:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1X9cDH-0001no-N0 for qemu-devel@nongnu.org; Tue, 22 Jul 2014 11:42:53 -0400 Sender: Paolo Bonzini Message-ID: <53CE8671.4070603@redhat.com> Date: Tue, 22 Jul 2014 17:42:41 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1406042801-28212-1-git-send-email-lersek@redhat.com> In-Reply-To: <1406042801-28212-1-git-send-email-lersek@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH for-2.1 for-stable] vmstate_xhci_event: fix unterminated field list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Laszlo Ersek , amit.shah@redhat.com, dgilbert@redhat.com, kraxel@redhat.com, qemu-devel@nongnu.org, qemu-stable@nongnu.org Il 22/07/2014 17:26, Laszlo Ersek ha scritto: > "vmstate_xhci_event" was introduced in commit 37352df3 ("xhci: add live > migration support"), and first released in v1.6.0. The field list in this > VMSD is not terminated with the VMSTATE_END_OF_LIST() macro. > > During normal use (ie. migration), the issue is practically invisible, > because the "vmstate_xhci_event" object (with the unterminated field list) > is only ever referenced -- via "vmstate_xhci_intr" -- if xhci_er_full() > returns true, for the "ev_buffer" test. Since that field_exists() check > (apparently) almost always returns false, we almost never traverse > "vmstate_xhci_event" during migration, which hides the bug. > > However, Amit's vmstate checker forces recursion into this VMSD as well, > and the lack of VMSTATE_END_OF_LIST() breaks the field list terminator > check (field->name != NULL) in dump_vmstate_vmsd(). The result is > undefined behavior, which in my case translates to infinite recursion > (because the loop happens to overflow into "vmstate_xhci_intr", which then > links back to "vmstate_xhci_event"). > > Add the missing terminator. > > Signed-off-by: Laszlo Ersek > --- > hw/usb/hcd-xhci.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/hw/usb/hcd-xhci.c b/hw/usb/hcd-xhci.c > index 7f2af89..58c4b11 100644 > --- a/hw/usb/hcd-xhci.c > +++ b/hw/usb/hcd-xhci.c > @@ -3737,6 +3737,7 @@ static const VMStateDescription vmstate_xhci_event = { > VMSTATE_UINT32(flags, XHCIEvent), > VMSTATE_UINT8(slotid, XHCIEvent), > VMSTATE_UINT8(epid, XHCIEvent), > + VMSTATE_END_OF_LIST() > } > }; > > Cc: qemu-stable@nongnu.org Reviewed-by: Paolo Bonzini