From fa1ed74eb1c233be6131ec92df21ab46499a15b6 Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Fri, 22 Sep 2017 23:43:46 +0300 Subject: [PATCH] USB: devio: Don't corrupt user memory The user buffer has "uurb->buffer_length" bytes. If the kernel has more information than that, we should truncate it instead of writing past the end of the user's buffer. I added a WARN_ONCE() to help the user debug the issue. Reported-by: Alan Stern Cc: stable Signed-off-by: Dan Carpenter Acked-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/devio.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index e9326f31db8d..4664e543cf2f 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -1576,7 +1576,11 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb totlen += isopkt[u].length; } u *= sizeof(struct usb_iso_packet_descriptor); - uurb->buffer_length = totlen; + if (totlen <= uurb->buffer_length) + uurb->buffer_length = totlen; + else + WARN_ONCE(1, "uurb->buffer_length is too short %d vs %d", + totlen, uurb->buffer_length); break; default: -- 2.11.0