From: Juergen Gross <jgross@suse.com> stable inclusion from linux-4.19.222 commit 269d7124bcfad2558d2329d0fe603ca20b20d3f4 CVE: CVE-2021-28711 -------------------------------- commit 0fd08a34e8e3b67ec9bd8287ac0facf8374b844a upstream. The Xen blkfront driver is still vulnerable for an attack via excessive number of events sent by the backend. Fix that by using lateeoi event channels. This is part of XSA-391 Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- drivers/block/xen-blkfront.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 90d6e13192bda..4e52917ebd311 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -1563,9 +1563,12 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id) unsigned long flags; struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id; struct blkfront_info *info = rinfo->dev_info; + unsigned int eoiflag = XEN_EOI_FLAG_SPURIOUS; - if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) + if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) { + xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS); return IRQ_HANDLED; + } spin_lock_irqsave(&rinfo->ring_lock, flags); again: @@ -1581,6 +1584,8 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id) unsigned long id; unsigned int op; + eoiflag = 0; + RING_COPY_RESPONSE(&rinfo->ring, i, &bret); id = bret.id; @@ -1696,6 +1701,8 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id) spin_unlock_irqrestore(&rinfo->ring_lock, flags); + xen_irq_lateeoi(irq, eoiflag); + return IRQ_HANDLED; err: @@ -1703,6 +1710,8 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id) spin_unlock_irqrestore(&rinfo->ring_lock, flags); + /* No EOI in order to avoid further interrupts. */ + pr_alert("%s disabled for further use\n", info->gd->disk_name); return IRQ_HANDLED; } @@ -1742,8 +1751,8 @@ static int setup_blkring(struct xenbus_device *dev, if (err) goto fail; - err = bind_evtchn_to_irqhandler(rinfo->evtchn, blkif_interrupt, 0, - "blkif", rinfo); + err = bind_evtchn_to_irqhandler_lateeoi(rinfo->evtchn, blkif_interrupt, + 0, "blkif", rinfo); if (err <= 0) { xenbus_dev_fatal(dev, err, "bind_evtchn_to_irqhandler failed"); -- 2.25.1