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* [PATCH] usbip: vhci_sysfs: fix potential Spectre v1
@ 2018-05-16 22:22 Gustavo A. R. Silva
  2018-05-17  6:51 ` Greg Kroah-Hartman
  0 siblings, 1 reply; 5+ messages in thread
From: Gustavo A. R. Silva @ 2018-05-16 22:22 UTC (permalink / raw)
  To: Valentina Manea, Shuah Khan, Greg Kroah-Hartman
  Cc: linux-usb, linux-kernel, Gustavo A. R. Silva

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].

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 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..9045888 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"
 
@@ -235,6 +237,8 @@ static ssize_t detach_store(struct device *dev, struct device_attribute *attr,
 	if (!valid_port(pdev_nr, rhport))
 		return -EINVAL;
 
+	pdev_nr = array_index_nospec(pdev_nr, vhci_num_controllers);
+	rhport = array_index_nospec(rhport, VHCI_HC_PORTS);
 	hcd = platform_get_drvdata(vhcis[pdev_nr].pdev);
 	if (hcd == NULL) {
 		dev_err(dev, "port is not ready %u\n", port);
@@ -325,6 +329,8 @@ static ssize_t attach_store(struct device *dev, struct device_attribute *attr,
 	if (!valid_args(pdev_nr, rhport, speed))
 		return -EINVAL;
 
+	pdev_nr = array_index_nospec(pdev_nr, vhci_num_controllers);
+	rhport = array_index_nospec(rhport, VHCI_HC_PORTS);
 	hcd = platform_get_drvdata(vhcis[pdev_nr].pdev);
 	if (hcd == NULL) {
 		dev_err(dev, "port %d is not ready\n", port);
-- 
2.7.4

^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2018-05-17 19:29 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-05-16 22:22 [PATCH] usbip: vhci_sysfs: fix potential Spectre v1 Gustavo A. R. Silva
2018-05-17  6:51 ` Greg Kroah-Hartman
2018-05-17 17:57   ` Gustavo A. R. Silva
2018-05-17 19:15     ` Greg Kroah-Hartman
2018-05-17 19:29       ` Gustavo A. R. Silva

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