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82 lines
2.8 KiB
82 lines
2.8 KiB
From f6f4388c917ce96b075a239a4535b8efc6064d14 Mon Sep 17 00:00:00 2001
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From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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Date: Mon, 16 Nov 2015 12:40:48 -0500
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Subject: [PATCH 7/7] xen/pciback: Save xen_pci_op commands before processing
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it
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Double fetch vulnerabilities that happen when a variable is
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fetched twice from shared memory but a security check is only
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performed the first time.
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The xen_pcibk_do_op function performs a switch statements on the op->cmd
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value which is stored in shared memory. Interestingly this can result
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in a double fetch vulnerability depending on the performed compiler
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optimization.
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This patch fixes it by saving the xen_pci_op command before
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processing it. We also use 'barrier' to make sure that the
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compiler does not perform any optimization.
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This is part of XSA155.
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CC: stable@vger.kernel.org
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Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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Signed-off-by: Jan Beulich <JBeulich@suse.com>
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Signed-off-by: David Vrabel <david.vrabel@citrix.com>
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Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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---
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drivers/xen/xen-pciback/pciback.h | 1 +
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drivers/xen/xen-pciback/pciback_ops.c | 15 ++++++++++++++-
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2 files changed, 15 insertions(+), 1 deletion(-)
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diff --git a/drivers/xen/xen-pciback/pciback.h b/drivers/xen/xen-pciback/pciback.h
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index 58e38d5..4d529f3 100644
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--- a/drivers/xen/xen-pciback/pciback.h
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+++ b/drivers/xen/xen-pciback/pciback.h
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@@ -37,6 +37,7 @@ struct xen_pcibk_device {
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struct xen_pci_sharedinfo *sh_info;
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unsigned long flags;
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struct work_struct op_work;
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+ struct xen_pci_op op;
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};
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struct xen_pcibk_dev_data {
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diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c
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index c4a0666..a0e0e3e 100644
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--- a/drivers/xen/xen-pciback/pciback_ops.c
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+++ b/drivers/xen/xen-pciback/pciback_ops.c
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@@ -298,9 +298,11 @@ void xen_pcibk_do_op(struct work_struct *data)
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container_of(data, struct xen_pcibk_device, op_work);
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struct pci_dev *dev;
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struct xen_pcibk_dev_data *dev_data = NULL;
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- struct xen_pci_op *op = &pdev->sh_info->op;
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+ struct xen_pci_op *op = &pdev->op;
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int test_intx = 0;
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+ *op = pdev->sh_info->op;
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+ barrier();
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dev = xen_pcibk_get_pci_dev(pdev, op->domain, op->bus, op->devfn);
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if (dev == NULL)
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@@ -342,6 +344,17 @@ void xen_pcibk_do_op(struct work_struct *data)
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if ((dev_data->enable_intx != test_intx))
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xen_pcibk_control_isr(dev, 0 /* no reset */);
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}
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+ pdev->sh_info->op.err = op->err;
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+ pdev->sh_info->op.value = op->value;
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+#ifdef CONFIG_PCI_MSI
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+ if (op->cmd == XEN_PCI_OP_enable_msix && op->err == 0) {
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+ unsigned int i;
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+
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+ for (i = 0; i < op->value; i++)
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+ pdev->sh_info->op.msix_entries[i].vector =
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+ op->msix_entries[i].vector;
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+ }
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+#endif
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/* Tell the driver domain that we're done. */
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wmb();
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clear_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags);
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--
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2.1.0
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