From fa1ed74eb1c233be6131ec92df21ab46499a15b6 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Fri, 22 Sep 2017 23:43:46 +0300
Subject: [PATCH] USB: devio: Don't corrupt user memory
Git-commit: fa1ed74eb1c233be6131ec92df21ab46499a15b6
Patch-mainline: v4.14-rc4
References: bsc#1085536
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 <stern@rowland.harvard.edu>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
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:
--
2.13.6