From a03ff54460817c76105f81f3aa8ef655759ccc9a Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Mon, 13 May 2019 13:14:29 -0400 Subject: [PATCH] USB: Fix slab-out-of-bounds write in usb_get_bos_descriptor The syzkaller USB fuzzer found a slab-out-of-bounds write bug in the USB core, caused by a failure to check the actual size of a BOS descriptor. This patch adds a check to make sure the descriptor is at least as large as it is supposed to be, so that the code doesn't inadvertently access memory beyond the end of the allocated region when assigning to dev->bos->desc->bNumDeviceCaps later on. Signed-off-by: Alan Stern Reported-and-tested-by: syzbot+71f1e64501a309fcc012@syzkaller.appspotmail.com CC: Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/config.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c index 20ff036b4c22..9d6cb709ca7b 100644 --- a/drivers/usb/core/config.c +++ b/drivers/usb/core/config.c @@ -932,8 +932,8 @@ int usb_get_bos_descriptor(struct usb_device *dev) /* Get BOS descriptor */ ret = usb_get_descriptor(dev, USB_DT_BOS, 0, bos, USB_DT_BOS_SIZE); - if (ret < USB_DT_BOS_SIZE) { - dev_err(ddev, "unable to get BOS descriptor\n"); + if (ret < USB_DT_BOS_SIZE || bos->bLength < USB_DT_BOS_SIZE) { + dev_err(ddev, "unable to get BOS descriptor or descriptor too short\n"); if (ret >= 0) ret = -ENOMSG; kfree(bos); -- GitLab