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Subject[034/156] virtio: fix out of range array access
2.6.33-stable review patch.  If anyone has any objections, please let us know.


From: Michael S. Tsirkin <>

commit 3119815912a220bdac943dfbdfee640414c0c611 upstream.

I have observed the following error on virtio-net module unload:

------------[ cut here ]------------
WARNING: at kernel/irq/manage.c:858 __free_irq+0xa0/0x14c()
Hardware name: Bochs
Trying to free already-free IRQ 0
Modules linked in: virtio_net(-) virtio_blk virtio_pci virtio_ring
virtio af_packet e1000 shpchp aacraid uhci_hcd ohci_hcd ehci_hcd [last
unloaded: scsi_wait_scan]
Pid: 1957, comm: rmmod Not tainted 2.6.33-rc8-vhost #24
Call Trace:
[<ffffffff8103e195>] warn_slowpath_common+0x7c/0x94
[<ffffffff8103e204>] warn_slowpath_fmt+0x41/0x43
[<ffffffff810a7a36>] ? __free_pages+0x5a/0x70
[<ffffffff8107cc00>] __free_irq+0xa0/0x14c
[<ffffffff8107cceb>] free_irq+0x3f/0x65
[<ffffffffa0081424>] vp_del_vqs+0x81/0xb1 [virtio_pci]
[<ffffffffa0091d29>] virtnet_remove+0xda/0x10b [virtio_net]
[<ffffffffa0075200>] virtio_dev_remove+0x22/0x4a [virtio]
[<ffffffff812709ee>] __device_release_driver+0x66/0xac
[<ffffffff81270ab7>] driver_detach+0x83/0xa9
[<ffffffff8126fc66>] bus_remove_driver+0x91/0xb4
[<ffffffff81270fcf>] driver_unregister+0x6c/0x74
[<ffffffffa0075418>] unregister_virtio_driver+0xe/0x10 [virtio]
[<ffffffffa0091c4d>] fini+0x15/0x17 [virtio_net]
[<ffffffff8106997b>] sys_delete_module+0x1c3/0x230
[<ffffffff81007465>] ? old_ich_force_enable_hpet+0x117/0x164
[<ffffffff813bb720>] ? do_page_fault+0x29c/0x2cc
[<ffffffff81028e58>] sysenter_dispatch+0x7/0x27
---[ end trace 15e88e4c576cc62b ]---

The bug is in virtio-pci: we use msix_vector as array index to get irq
entry, but some vqs do not have a dedicated vector so this causes an out
of bounds access. By chance, we seem to often get 0 value, which
results in this error.

Fix by verifying that vector is legal before using it as index.

Signed-off-by: Michael S. Tsirkin <>
Acked-by: Anthony Liguori <>
Acked-by: Shirley Ma <>
Acked-by: Amit Shah <>
Signed-off-by: Greg Kroah-Hartman <>

drivers/virtio/virtio_pci.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -473,7 +473,8 @@ static void vp_del_vqs(struct virtio_dev

list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
info = vq->priv;
- if (vp_dev->per_vq_vectors)
+ if (vp_dev->per_vq_vectors &&
+ info->msix_vector != VIRTIO_MSI_NO_VECTOR)

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