diff options
authorKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2015-11-02 18:07:44 -0500
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2015-12-18 10:48:29 -0500
commit5e0ce1455c09dd61d029b8ad45d82e1ac0b6c4c9 (patch)
parentxen/pciback: Return error on XEN_PCI_OP_enable_msi when device has MSI or MSI-X enabled (diff)
xen/pciback: Return error on XEN_PCI_OP_enable_msix when device has MSI or MSI-X enabled
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 CC: stable@vger.kernel.org Reviewed-by: David Vrabel <david.vrabel@citrix.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c
index 8bfb87c1a9f3..029f33ddb8bf 100644
--- a/drivers/xen/xen-pciback/pciback_ops.c
+++ b/drivers/xen/xen-pciback/pciback_ops.c
@@ -206,9 +206,16 @@ int xen_pcibk_enable_msix(struct xen_pcibk_device *pdev,
if (unlikely(verbose_request))
printk(KERN_DEBUG DRV_NAME ": %s: enable MSI-X\n",
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;