lkml.org 
[lkml]   [2016]   [Oct]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 3.4 098/125] xen/pciback: Return error on XEN_PCI_OP_enable_msix when device has MSI or MSI-X enabled
Date
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

3.4.113-rc1 review patch. If anyone has any objections, please let me know.

------------------


commit 5e0ce1455c09dd61d029b8ad45d82e1ac0b6c4c9 upstream.

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

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>
Signed-off-by: Zefan Li <lizefan@huawei.com>
---
drivers/xen/xen-pciback/pciback_ops.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c
index 1ab998c..f7ce4de 100644
--- a/drivers/xen/xen-pciback/pciback_ops.c
+++ b/drivers/xen/xen-pciback/pciback_ops.c
@@ -205,9 +205,16 @@ int xen_pcibk_enable_msix(struct xen_pcibk_device *pdev,
if (unlikely(verbose_request))
printk(KERN_DEBUG DRV_NAME ": %s: enable MSI-X\n",
pci_name(dev));
+
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;
--
1.9.1
\
 
 \ /
  Last update: 2016-10-12 15:02    [W:0.422 / U:0.044 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site