diff options
| author | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2015-11-16 12:40:48 -0500 |
|---|---|---|
| committer | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2015-12-18 10:00:47 -0500 |
| commit | 8135cf8b092723dbfcc611fe6fdcb3a36c9951c5 (patch) | |
| tree | d1f03969e8a2af5ff9e2b2ea8eaab58405ac30eb | |
| parent | be69746ec12f35b484707da505c6c76ff06f97dc (diff) | |
| download | linux-btrfs-8135cf8b092723dbfcc611fe6fdcb3a36c9951c5.tar.gz | |
xen/pciback: Save xen_pci_op commands before processing it
Double fetch vulnerabilities that happen when a variable is
fetched twice from shared memory but a security check is only
performed the first time.
The xen_pcibk_do_op function performs a switch statements on the op->cmd
value which is stored in shared memory. Interestingly this can result
in a double fetch vulnerability depending on the performed compiler
optimization.
This patch fixes it by saving the xen_pci_op command before
processing it. We also use 'barrier' to make sure that the
compiler does not perform any optimization.
This is part of XSA155.
CC: stable@vger.kernel.org
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jan Beulich <JBeulich@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
| -rw-r--r-- | drivers/xen/xen-pciback/pciback.h | 1 | ||||
| -rw-r--r-- | drivers/xen/xen-pciback/pciback_ops.c | 15 |
2 files changed, 15 insertions, 1 deletions
diff --git a/drivers/xen/xen-pciback/pciback.h b/drivers/xen/xen-pciback/pciback.h index 58e38d586f524f..4d529f3e40df93 100644 --- a/drivers/xen/xen-pciback/pciback.h +++ b/drivers/xen/xen-pciback/pciback.h @@ -37,6 +37,7 @@ struct xen_pcibk_device { struct xen_pci_sharedinfo *sh_info; unsigned long flags; struct work_struct op_work; + struct xen_pci_op op; }; struct xen_pcibk_dev_data { diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c index c4a0666de6f5e0..a0e0e3ed4905c1 100644 --- a/drivers/xen/xen-pciback/pciback_ops.c +++ b/drivers/xen/xen-pciback/pciback_ops.c @@ -298,9 +298,11 @@ void xen_pcibk_do_op(struct work_struct *data) container_of(data, struct xen_pcibk_device, op_work); struct pci_dev *dev; struct xen_pcibk_dev_data *dev_data = NULL; - struct xen_pci_op *op = &pdev->sh_info->op; + struct xen_pci_op *op = &pdev->op; int test_intx = 0; + *op = pdev->sh_info->op; + barrier(); dev = xen_pcibk_get_pci_dev(pdev, op->domain, op->bus, op->devfn); if (dev == NULL) @@ -342,6 +344,17 @@ void xen_pcibk_do_op(struct work_struct *data) if ((dev_data->enable_intx != test_intx)) xen_pcibk_control_isr(dev, 0 /* no reset */); } + pdev->sh_info->op.err = op->err; + pdev->sh_info->op.value = op->value; +#ifdef CONFIG_PCI_MSI + if (op->cmd == XEN_PCI_OP_enable_msix && op->err == 0) { + unsigned int i; + + for (i = 0; i < op->value; i++) + pdev->sh_info->op.msix_entries[i].vector = + op->msix_entries[i].vector; + } +#endif /* Tell the driver domain that we're done. */ wmb(); clear_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags); |