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Subject[PATCH v2] usbip: vhci_sysfs: fix potential Spectre v1
pdev_nr and rhport can be controlled by user-space, hence leading to
a potential exploitation of the Spectre variant 1 vulnerability.

This issue was detected with the help of Smatch:
drivers/usb/usbip/vhci_sysfs.c:238 detach_store() warn: potential spectre issue 'vhcis'
drivers/usb/usbip/vhci_sysfs.c:328 attach_store() warn: potential spectre issue 'vhcis'
drivers/usb/usbip/vhci_sysfs.c:338 attach_store() warn: potential spectre issue 'vhci->vhci_hcd_ss->vdev'
drivers/usb/usbip/vhci_sysfs.c:340 attach_store() warn: potential spectre issue 'vhci->vhci_hcd_hs->vdev'

Fix this by sanitizing pdev_nr and rhport before using them to index
vhcis and vhci->vhci_hcd_ss->vdev respectively.

Notice that given that speculation windows are large, the policy is
to kill the speculation on the first load and not worry if it can be
completed with a dependent load/store [1].


Signed-off-by: Gustavo A. R. Silva <>
Changes in v2:
- Place the barriers into valid_port.

drivers/usb/usbip/vhci_sysfs.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/drivers/usb/usbip/vhci_sysfs.c b/drivers/usb/usbip/vhci_sysfs.c
index 4880838..69db0c9 100644
--- a/drivers/usb/usbip/vhci_sysfs.c
+++ b/drivers/usb/usbip/vhci_sysfs.c
@@ -10,6 +10,8 @@
#include <linux/platform_device.h>
#include <linux/slab.h>

+#include <linux/nospec.h>
#include "usbip_common.h"
#include "vhci.h"

@@ -211,10 +213,14 @@ static int valid_port(__u32 pdev_nr, __u32 rhport)
pr_err("pdev %u\n", pdev_nr);
return 0;
+ pdev_nr = array_index_nospec(pdev_nr, vhci_num_controllers);
if (rhport >= VHCI_HC_PORTS) {
pr_err("rhport %u\n", rhport);
return 0;
+ rhport = array_index_nospec(rhport, VHCI_HC_PORTS);
return 1;

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