From: Konrad Rzeszutek Wilk <konrad.w...@oracle.com> 3.4.113-rc1 review patch. If anyone has any objections, please let me know.
------------------ commit 5e0ce1455c09dd61d029b8ad45d82e1ac0b6c4c9 upstream. The guest sequence of: a) XEN_PCI_OP_enable_msix b) XEN_PCI_OP_enable_msix results in hitting an NULL pointer due to using freed pointers. The device passed in the guest MUST have MSI-X capability. The a) constructs and SysFS representation of MSI and MSI groups. The b) adds a second set of them but adding in to SysFS fails (duplicate entry). 'populate_msi_sysfs' frees the newly allocated msi_irq_groups (note that in a) pdev->msi_irq_groups is still set) and also free's ALL of the MSI-X entries of the device (the ones allocated in step a) and b)). The unwind code: 'free_msi_irqs' deletes all the entries and tries to delete the pdev->msi_irq_groups (which hasn't been set to NULL). However the pointers in the SysFS are already freed and we hit an NULL pointer further on when 'strlen' is attempted on a freed pointer. The patch adds a simple check in the XEN_PCI_OP_enable_msix to guard against that. The check for msi_enabled is not stricly neccessary. This is part of XSA-157 Reviewed-by: David Vrabel <david.vra...@citrix.com> Reviewed-by: Jan Beulich <jbeul...@suse.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.w...@oracle.com> Signed-off-by: Zefan Li <lize...@huawei.com> --- drivers/xen/xen-pciback/pciback_ops.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c index 1ab998c..f7ce4de 100644 --- a/drivers/xen/xen-pciback/pciback_ops.c +++ b/drivers/xen/xen-pciback/pciback_ops.c @@ -205,9 +205,16 @@ int xen_pcibk_enable_msix(struct xen_pcibk_device *pdev, if (unlikely(verbose_request)) printk(KERN_DEBUG DRV_NAME ": %s: enable MSI-X\n", pci_name(dev)); + if (op->value > SH_INFO_MAX_VEC) return -EINVAL; + if (dev->msix_enabled) + return -EALREADY; + + if (dev->msi_enabled) + return -ENXIO; + entries = kmalloc(op->value * sizeof(*entries), GFP_KERNEL); if (entries == NULL) return -ENOMEM; -- 1.9.1