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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>
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1 changed files with 6 additions and 1 deletions
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@ -144,7 +144,12 @@ int xen_pcibk_enable_msi(struct xen_pcibk_device *pdev,
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if (unlikely(verbose_request))
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if (unlikely(verbose_request))
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printk(KERN_DEBUG DRV_NAME ": %s: enable MSI\n", pci_name(dev));
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printk(KERN_DEBUG DRV_NAME ": %s: enable MSI\n", pci_name(dev));
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status = pci_enable_msi(dev);
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if (dev->msi_enabled)
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status = -EALREADY;
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else if (dev->msix_enabled)
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status = -ENXIO;
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else
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status = pci_enable_msi(dev);
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if (status) {
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if (status) {
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pr_warn_ratelimited("%s: error enabling MSI for guest %u: err %d\n",
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pr_warn_ratelimited("%s: error enabling MSI for guest %u: err %d\n",
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