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virtio_pci: fix out of bound access for msix_names 

Fedora has received multiple reports of crashes when running
4.11 as a guest

https://bugzilla.redhat.com/show_bug.cgi?id=1430297
https://bugzilla.redhat.com/show_bug.cgi?id=1434462
https://bugzilla.kernel.org/show_bug.cgi?id=194911
https://bugzilla.redhat.com/show_bug.cgi?id=1433899

The crashes are not always consistent but they are generally
some flavor of oops or GPF in virtio related code. Multiple people
have done bisections (Thank you Thorsten Leemhuis and
Richard W.M. Jones) and found this commit to be at fault

07ec51480b is the first bad commit
commit 07ec51480b
Author: Christoph Hellwig <hch@lst.de>
Date:   Sun Feb 5 18:15:19 2017 +0100

    virtio_pci: use shared interrupts for virtqueues

The issue seems to be an out of bounds access to the msix_names
array corrupting kernel memory.

Fixes: 07ec51480b ("virtio_pci: use shared interrupts for virtqueues")
Reported-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Richard W.M. Jones <rjones@redhat.com>
Tested-by: Thorsten Leemhuis <linux@leemhuis.info>
This commit is contained in:
Jason Wang 2017-03-23 13:07:16 +08:00 committed by Michael S. Tsirkin
parent c02ed2e75e
commit de85ec8b07
1 changed files with 5 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
drivers/virtio/virtio_pci_common.c
View File

@ -147,7 +147,7 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
const char *name = dev_name(&vp_dev->vdev.dev);
int i, err = -ENOMEM, allocated_vectors, nvectors;
int i, j, err = -ENOMEM, allocated_vectors, nvectors;
unsigned flags = PCI_IRQ_MSIX;
bool shared = false;
u16 msix_vec;
@ -212,7 +212,7 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
if (!vp_dev->msix_vector_map)
goto out_disable_config_irq;
allocated_vectors = 1; /* vector 0 is the config interrupt */
allocated_vectors = j = 1; /* vector 0 is the config interrupt */
for (i = 0; i < nvqs; ++i) {
if (!names[i]) {
vqs[i] = NULL;
@ -236,18 +236,19 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
continue;
}
snprintf(vp_dev->msix_names[i + 1],
snprintf(vp_dev->msix_names[j],
sizeof(*vp_dev->msix_names), "%s-%s",
dev_name(&vp_dev->vdev.dev), names[i]);
err = request_irq(pci_irq_vector(vp_dev->pci_dev, msix_vec),
vring_interrupt, IRQF_SHARED,
vp_dev->msix_names[i + 1], vqs[i]);
vp_dev->msix_names[j], vqs[i]);
if (err) {
/* don't free this irq on error */
vp_dev->msix_vector_map[i] = VIRTIO_MSI_NO_VECTOR;
goto out_remove_vqs;
}
vp_dev->msix_vector_map[i] = msix_vec;
j++;
/*
* Use a different vector for each queue if they are available,