The hard limit sounds good to me. But if you want to centralize error handling, please make sure that "goto done" only frees map, but not map->menu_info in that case. - Haogang On Tue, Nov 29, 2011 at 8:22 PM, Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> wrote: > Hi Haogang, > > On Tuesday 29 November 2011 22:32:25 Haogang Chen wrote: >> There is a potential integer overflow in uvc_ioctl_ctrl_map(). When a >> large xmap->menu_count is passed from the userspace, the subsequent call >> to kmalloc() will allocate a buffer smaller than expected. >> map->menu_count and map->menu_info would later be used in a loop (e.g. >> in uvc_query_v4l2_ctrl), which leads to out-of-bound access. >> >> The patch checks the ioctl argument and returns -EINVAL for zero or too >> large values in xmap->menu_count. > > Thanks for the patch. > >> Signed-off-by: Haogang Chen <haogangchen@xxxxxxxxx> >> --- >> drivers/media/video/uvc/uvc_v4l2.c | 6 ++++++ >> 1 files changed, 6 insertions(+), 0 deletions(-) >> >> diff --git a/drivers/media/video/uvc/uvc_v4l2.c >> b/drivers/media/video/uvc/uvc_v4l2.c index dadf11f..9a180d6 100644 >> --- a/drivers/media/video/uvc/uvc_v4l2.c >> +++ b/drivers/media/video/uvc/uvc_v4l2.c >> @@ -58,6 +58,12 @@ static int uvc_ioctl_ctrl_map(struct uvc_video_chain >> *chain, break; >> >> case V4L2_CTRL_TYPE_MENU: >> + if (xmap->menu_count == 0 || >> + xmap->menu_count > INT_MAX / sizeof(*map->menu_info)) { > > I'd like to prevent excessive memory consumption by limiting the number of > menu entries, similarly to how the driver limits the number of mappings. > Defining UVC_MAX_CONTROL_MENU_ENTRIES to 32 in uvcvideo.h should be a > reasonable value. > >> + kfree(map); >> + return -EINVAL; > > I'd rather do > > ret = -EINVAL; > goto done; > > to centralize error handling. > > If you're fine with both changes I can modify the patch, there's no need to > resubmit. > >> + } >> + >> size = xmap->menu_count * sizeof(*map->menu_info); >> map->menu_info = kmalloc(size, GFP_KERNEL); >> if (map->menu_info == NULL) { > > -- > Regards, > > Laurent Pinchart > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html