1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
|
From f6f4388c917ce96b075a239a4535b8efc6064d14 Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Date: Mon, 16 Nov 2015 12:40:48 -0500
Subject: [PATCH 7/7] xen/pciback: Save xen_pci_op commands before processing
it
Double fetch vulnerabilities that happen when a variable is
fetched twice from shared memory but a security check is only
performed the first time.
The xen_pcibk_do_op function performs a switch statements on the op->cmd
value which is stored in shared memory. Interestingly this can result
in a double fetch vulnerability depending on the performed compiler
optimization.
This patch fixes it by saving the xen_pci_op command before
processing it. We also use 'barrier' to make sure that the
compiler does not perform any optimization.
This is part of XSA155.
CC: stable@vger.kernel.org
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jan Beulich <JBeulich@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
drivers/xen/xen-pciback/pciback.h | 1 +
drivers/xen/xen-pciback/pciback_ops.c | 15 ++++++++++++++-
2 files changed, 15 insertions(+), 1 deletion(-)
diff --git a/drivers/xen/xen-pciback/pciback.h b/drivers/xen/xen-pciback/pciback.h
index 58e38d5..4d529f3 100644
--- a/drivers/xen/xen-pciback/pciback.h
+++ b/drivers/xen/xen-pciback/pciback.h
@@ -37,6 +37,7 @@ struct xen_pcibk_device {
struct xen_pci_sharedinfo *sh_info;
unsigned long flags;
struct work_struct op_work;
+ struct xen_pci_op op;
};
struct xen_pcibk_dev_data {
diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c
index c4a0666..a0e0e3e 100644
--- a/drivers/xen/xen-pciback/pciback_ops.c
+++ b/drivers/xen/xen-pciback/pciback_ops.c
@@ -298,9 +298,11 @@ void xen_pcibk_do_op(struct work_struct *data)
container_of(data, struct xen_pcibk_device, op_work);
struct pci_dev *dev;
struct xen_pcibk_dev_data *dev_data = NULL;
- struct xen_pci_op *op = &pdev->sh_info->op;
+ struct xen_pci_op *op = &pdev->op;
int test_intx = 0;
+ *op = pdev->sh_info->op;
+ barrier();
dev = xen_pcibk_get_pci_dev(pdev, op->domain, op->bus, op->devfn);
if (dev == NULL)
@@ -342,6 +344,17 @@ void xen_pcibk_do_op(struct work_struct *data)
if ((dev_data->enable_intx != test_intx))
xen_pcibk_control_isr(dev, 0 /* no reset */);
}
+ pdev->sh_info->op.err = op->err;
+ pdev->sh_info->op.value = op->value;
+#ifdef CONFIG_PCI_MSI
+ if (op->cmd == XEN_PCI_OP_enable_msix && op->err == 0) {
+ unsigned int i;
+
+ for (i = 0; i < op->value; i++)
+ pdev->sh_info->op.msix_entries[i].vector =
+ op->msix_entries[i].vector;
+ }
+#endif
/* Tell the driver domain that we're done. */
wmb();
clear_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags);
--
2.1.0
|
