Messages in this thread | | | Subject | Re: [PATCH v3] usbip: vhci_sysfs: fix potential Spectre v1 | From | "Gustavo A. R. Silva" <> | Date | Tue, 22 May 2018 11:07:38 -0500 |
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On 05/22/2018 10:56 AM, Shuah Khan wrote: > 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: stable@vger.kernel.org >> Signed-off-by: Gustavo A. R. Silva <gustavo@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. >
Glad to help. :)
> Acked-by: Shuah Khan (Samsung OSG) <shuah@kernel.org> >
Thanks -- Gustavo
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