uref->field_index, uref->usage_index, finfo.field_index and cinfo.index can be indirectly 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/hid/usbhid/hiddev.c:473 hiddev_ioctl_usage() warn: potential spectre issue 'report->field' (local cap) drivers/hid/usbhid/hiddev.c:477 hiddev_ioctl_usage() warn: potential spectre issue 'field->usage' (local cap) drivers/hid/usbhid/hiddev.c:757 hiddev_ioctl() warn: potential spectre issue 'report->field' (local cap) drivers/hid/usbhid/hiddev.c:801 hiddev_ioctl() warn: potential spectre issue 'hid->collection' (local cap) Fix this by sanitizing such structure fields before using them to index report->field, field->usage and hid->collection 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@xxxxxxxxxxxxxxx Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx> --- drivers/hid/usbhid/hiddev.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/hid/usbhid/hiddev.c b/drivers/hid/usbhid/hiddev.c index e3ce233..23872d0 100644 --- a/drivers/hid/usbhid/hiddev.c +++ b/drivers/hid/usbhid/hiddev.c @@ -36,6 +36,7 @@ #include <linux/hiddev.h> #include <linux/compat.h> #include <linux/vmalloc.h> +#include <linux/nospec.h> #include "usbhid.h" #ifdef CONFIG_USB_DYNAMIC_MINORS @@ -469,10 +470,14 @@ static noinline int hiddev_ioctl_usage(struct hiddev *hiddev, unsigned int cmd, if (uref->field_index >= report->maxfield) goto inval; + uref->field_index = array_index_nospec(uref->field_index, + report->maxfield); field = report->field[uref->field_index]; if (uref->usage_index >= field->maxusage) goto inval; + uref->usage_index = array_index_nospec(uref->usage_index, + field->maxusage); uref->usage_code = field->usage[uref->usage_index].hid; @@ -499,6 +504,8 @@ static noinline int hiddev_ioctl_usage(struct hiddev *hiddev, unsigned int cmd, if (uref->field_index >= report->maxfield) goto inval; + uref->field_index = array_index_nospec(uref->field_index, + report->maxfield); field = report->field[uref->field_index]; @@ -753,6 +760,8 @@ static long hiddev_ioctl(struct file *file, unsigned int cmd, unsigned long arg) if (finfo.field_index >= report->maxfield) break; + finfo.field_index = array_index_nospec(finfo.field_index, + report->maxfield); field = report->field[finfo.field_index]; memset(&finfo, 0, sizeof(finfo)); @@ -797,6 +806,8 @@ static long hiddev_ioctl(struct file *file, unsigned int cmd, unsigned long arg) if (cinfo.index >= hid->maxcollection) break; + cinfo.index = array_index_nospec(cinfo.index, + hid->maxcollection); cinfo.type = hid->collection[cinfo.index].type; cinfo.usage = hid->collection[cinfo.index].usage; -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
