On 05/18/2018 07:13 PM, Gustavo A. R. Silva wrote: > 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 v3: > - Pass the addresses of pdev_nr and rhport into valid_port and > valid_args. > > Changes in v2: > - Place the barriers into valid_port. > > drivers/usb/usbip/vhci_sysfs.c | 24 ++++++++++++++++-------- > 1 file changed, 16 insertions(+), 8 deletions(-) > > diff --git a/drivers/usb/usbip/vhci_sysfs.c b/drivers/usb/usbip/vhci_sysfs.c > index 4880838..be37aec 100644 > --- 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 vhci_hcd > *vhci_hcd, __u32 rhport) > 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 device *dev, struct > device_attribute *attr, > 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 device *dev, struct > device_attribute *attr, > } > 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 device *dev, struct > device_attribute *attr, > 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); >
Looks good to me. Thanks for taking care of this. Acked-by: Shuah Khan (Samsung OSG) <sh...@kernel.org> -- Shuah
