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authorKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2015-04-03 11:08:22 -0400
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2015-12-18 10:48:19 -0500
commit56441f3c8e5bd45aab10dd9f8c505dd4bec03b0d (patch)
tree35418204ad4079065a973a5cf63b715ab63e6e92 /drivers/xen
parent8135cf8b092723dbfcc611fe6fdcb3a36c9951c5 (diff)
downloadlinux-56441f3c8e5bd45aab10dd9f8c505dd4bec03b0d.tar.bz2
xen/pciback: Return error on XEN_PCI_OP_enable_msi when device has MSI or MSI-X enabled
The guest sequence of: a) XEN_PCI_OP_enable_msi b) XEN_PCI_OP_enable_msi c) XEN_PCI_OP_disable_msi results in hitting an BUG_ON condition in the msi.c code. The MSI code uses an dev->msi_list to which it adds MSI entries. Under the above conditions an BUG_ON() can be hit. The device passed in the guest MUST have MSI capability. The a) adds the entry to the dev->msi_list and sets msi_enabled. The b) adds a second entry but adding in to SysFS fails (duplicate entry) and deletes all of the entries from msi_list and returns (with msi_enabled is still set). c) pci_disable_msi passes the msi_enabled checks and hits: BUG_ON(list_empty(dev_to_msi_list(&dev->dev))); and blows up. The patch adds a simple check in the XEN_PCI_OP_enable_msi to guard against that. The check for msix_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>
Diffstat (limited to 'drivers/xen')
-rw-r--r--drivers/xen/xen-pciback/pciback_ops.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c
index a0e0e3ed4905..8bfb87c1a9f3 100644
--- a/drivers/xen/xen-pciback/pciback_ops.c
+++ b/drivers/xen/xen-pciback/pciback_ops.c
@@ -144,7 +144,12 @@ int xen_pcibk_enable_msi(struct xen_pcibk_device *pdev,
if (unlikely(verbose_request))
printk(KERN_DEBUG DRV_NAME ": %s: enable MSI\n", pci_name(dev));
- status = pci_enable_msi(dev);
+ if (dev->msi_enabled)
+ status = -EALREADY;
+ else if (dev->msix_enabled)
+ status = -ENXIO;
+ else
+ status = pci_enable_msi(dev);
if (status) {
pr_warn_ratelimited("%s: error enabling MSI for guest %u: err %d\n",