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: sta...@vger.kernel.org Signed-off-by: Gustavo A. R. Silva <gust...@embeddedor.com> --- 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; } -- 2.7.4
