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Date:      Sat, 29 Aug 2015 06:17:40 +0000 (UTC)
From:      Hans Petter Selasky <hselasky@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-9@freebsd.org
Subject:   svn commit: r287273 - stable/9/sys/dev/usb
Message-ID:  <201508290617.t7T6HeXG029304@repo.freebsd.org>
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Author: hselasky
Date: Sat Aug 29 06:17:39 2015
New Revision: 287273
URL: https://svnweb.freebsd.org/changeset/base/287273

Log:
  MFC r286799:
  Fix race in USB PF which can happen if we stop tracing exactly when
  the kernel is tapping an USB transfer. This leads to a NULL pointer
  access. The solution is to only trace while the USB bus lock is
  locked.

Modified:
  stable/9/sys/dev/usb/usb_pf.c
  stable/9/sys/dev/usb/usb_transfer.c
Directory Properties:
  stable/9/sys/   (props changed)
  stable/9/sys/dev/   (props changed)

Modified: stable/9/sys/dev/usb/usb_pf.c
==============================================================================
--- stable/9/sys/dev/usb/usb_pf.c	Sat Aug 29 06:11:50 2015	(r287272)
+++ stable/9/sys/dev/usb/usb_pf.c	Sat Aug 29 06:17:39 2015	(r287273)
@@ -103,13 +103,16 @@ usbpf_detach(struct usb_bus *ubus)
 {
 	struct ifnet *ifp = ubus->ifp;
 
+	USB_BUS_LOCK(ubus);
+	ubus->ifp = NULL;
+	USB_BUS_UNLOCK(ubus);
+
 	if (ifp != NULL) {
 		bpfdetach(ifp);
 		if_down(ifp);
 		if_detach(ifp);
 		if_free(ifp);
 	}
-	ubus->ifp = NULL;
 }
 
 static uint32_t

Modified: stable/9/sys/dev/usb/usb_transfer.c
==============================================================================
--- stable/9/sys/dev/usb/usb_transfer.c	Sat Aug 29 06:11:50 2015	(r287272)
+++ stable/9/sys/dev/usb/usb_transfer.c	Sat Aug 29 06:17:39 2015	(r287273)
@@ -2292,8 +2292,11 @@ usbd_callback_wrapper(struct usb_xfer_qu
 	}
 
 #if USB_HAVE_PF
-	if (xfer->usb_state != USB_ST_SETUP)
+	if (xfer->usb_state != USB_ST_SETUP) {
+		USB_BUS_LOCK(info->bus);
 		usbpf_xfertap(xfer, USBPF_XFERTAP_DONE);
+		USB_BUS_UNLOCK(info->bus);
+	}
 #endif
 	/* call processing routine */
 	(xfer->callback) (xfer, xfer->error);

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