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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org,
        "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
        "Oliver Neukum" <oneukum@suse.com>,
        syzbot+843efa30c8821bd69f53@syzkaller.appspotmail.com
Date:   Sun, 09 Dec 2018 21:50:33 +0000
Message-ID: <lsq.1544392233.480859612@decadent.org.uk>
Subject: [PATCH 3.16 251/328] USB: usbdevfs: sanitize flags more
In-Reply-To: <lsq.1544392232.713909046@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

3.16.62-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Oliver Neukum <oneukum@suse.com>

commit 7a68d9fb851012829c29e770621905529bd9490b upstream.

Requesting a ZERO_PACKET or not is sensible only for output.
In the input direction the device decides.
Likewise accepting short packets makes sense only for input.

This allows operation with panic_on_warn without opening up
a local DOS.

Signed-off-by: Oliver Neukum <oneukum@suse.com>
Reported-by: syzbot+843efa30c8821bd69f53@syzkaller.appspotmail.com
Fixes: 0cb54a3e47cb ("USB: debugging code shouldn't alter control flow")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 drivers/usb/core/devio.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -1291,10 +1291,13 @@ static int proc_do_submiturb(struct usb_
 	struct async *as = NULL;
 	struct usb_ctrlrequest *dr = NULL;
 	unsigned int u, totlen, isofrmlen;
-	int i, ret, is_in, num_sgs = 0, ifnum = -1;
+	int i, ret, num_sgs = 0, ifnum = -1;
 	int number_of_packets = 0;
 	unsigned int stream_id = 0;
 	void *buf;
+	bool is_in;
+	bool allow_short = false;
+	bool allow_zero = false;
 	unsigned long mask =	USBDEVFS_URB_SHORT_NOT_OK |
 				USBDEVFS_URB_BULK_CONTINUATION |
 				USBDEVFS_URB_NO_FSBR |
@@ -1326,6 +1329,8 @@ static int proc_do_submiturb(struct usb_
 	u = 0;
 	switch(uurb->type) {
 	case USBDEVFS_URB_TYPE_CONTROL:
+		if (is_in)
+			allow_short = true;
 		if (!usb_endpoint_xfer_control(&ep->desc))
 			return -EINVAL;
 		/* min 8 byte setup packet */
@@ -1366,6 +1371,10 @@ static int proc_do_submiturb(struct usb_
 		break;
 
 	case USBDEVFS_URB_TYPE_BULK:
+		if (!is_in)
+			allow_zero = true;
+		else
+			allow_short = true;
 		switch (usb_endpoint_type(&ep->desc)) {
 		case USB_ENDPOINT_XFER_CONTROL:
 		case USB_ENDPOINT_XFER_ISOC:
@@ -1386,6 +1395,10 @@ static int proc_do_submiturb(struct usb_
 		if (!usb_endpoint_xfer_int(&ep->desc))
 			return -EINVAL;
  interrupt_urb:
+		if (!is_in)
+			allow_zero = true;
+		else
+			allow_short = true;
 		break;
 
 	case USBDEVFS_URB_TYPE_ISO:
@@ -1515,11 +1528,11 @@ static int proc_do_submiturb(struct usb_
 	u = (is_in ? URB_DIR_IN : URB_DIR_OUT);
 	if (uurb->flags & USBDEVFS_URB_ISO_ASAP)
 		u |= URB_ISO_ASAP;
-	if (uurb->flags & USBDEVFS_URB_SHORT_NOT_OK && is_in)
+	if (allow_short && uurb->flags & USBDEVFS_URB_SHORT_NOT_OK)
 		u |= URB_SHORT_NOT_OK;
 	if (uurb->flags & USBDEVFS_URB_NO_FSBR)
 		u |= URB_NO_FSBR;
-	if (uurb->flags & USBDEVFS_URB_ZERO_PACKET)
+	if (allow_zero && uurb->flags & USBDEVFS_URB_ZERO_PACKET)
 		u |= URB_ZERO_PACKET;
 	if (uurb->flags & USBDEVFS_URB_NO_INTERRUPT)
 		u |= URB_NO_INTERRUPT;