4.17-stable review patch. If anyone has any objections, please let me know.
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From: Gustavo A. R. Silva gustavo@embeddedor.com
commit a0d6ec88090d7b1b008429c44532a388e29bb1bd upstream.
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 Acked-by: Shuah Khan (Samsung OSG) shuah@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/usb/usbip/vhci_sysfs.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-)
--- a/drivers/usb/usbip/vhci_sysfs.c +++ b/drivers/usb/usbip/vhci_sysfs.c @@ -10,6 +10,9 @@ #include <linux/platform_device.h> #include <linux/slab.h>
+/* Hardening for Spectre-v1 */ +#include <linux/nospec.h> + #include "usbip_common.h" #include "vhci.h"
@@ -205,16 +208,20 @@ static int vhci_port_disconnect(struct v return 0; }
-static int valid_port(__u32 pdev_nr, __u32 rhport) +static int valid_port(__u32 *pdev_nr, __u32 *rhport) { - if (pdev_nr >= vhci_num_controllers) { - pr_err("pdev %u\n", pdev_nr); + if (*pdev_nr >= vhci_num_controllers) { + pr_err("pdev %u\n", *pdev_nr); return 0; } - if (rhport >= VHCI_HC_PORTS) { - pr_err("rhport %u\n", rhport); + *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; }
@@ -232,7 +239,7 @@ static ssize_t detach_store(struct devic pdev_nr = port_to_pdev_nr(port); rhport = port_to_rhport(port);
- if (!valid_port(pdev_nr, rhport)) + if (!valid_port(&pdev_nr, &rhport)) return -EINVAL;
hcd = platform_get_drvdata(vhcis[pdev_nr].pdev); @@ -258,7 +265,8 @@ static ssize_t detach_store(struct devic } static DEVICE_ATTR_WO(detach);
-static int valid_args(__u32 pdev_nr, __u32 rhport, enum usb_device_speed speed) +static int valid_args(__u32 *pdev_nr, __u32 *rhport, + enum usb_device_speed speed) { if (!valid_port(pdev_nr, rhport)) { return 0; @@ -322,7 +330,7 @@ static ssize_t attach_store(struct devic sockfd, devid, speed);
/* check received parameters */ - if (!valid_args(pdev_nr, rhport, speed)) + if (!valid_args(&pdev_nr, &rhport, speed)) return -EINVAL;
hcd = platform_get_drvdata(vhcis[pdev_nr].pdev);