From 7fcf000056a7b04a5ba2034f4556400e071c68b6 Mon Sep 17 00:00:00 2001 From: hselasky Date: Sat, 29 Aug 2015 06:11:50 +0000 Subject: [PATCH] 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. git-svn-id: svn://svn.freebsd.org/base/stable/10@287272 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f --- sys/dev/usb/usb_pf.c | 6 ++++++ sys/dev/usb/usb_transfer.c | 5 ++++- 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/sys/dev/usb/usb_pf.c b/sys/dev/usb/usb_pf.c index 27ab5f7d0..8c47e79b6 100644 --- a/sys/dev/usb/usb_pf.c +++ b/sys/dev/usb/usb_pf.c @@ -220,7 +220,13 @@ usbpf_clone_destroy(struct if_clone *ifc, struct ifnet *ifp) ubus = ifp->if_softc; unit = ifp->if_dunit; + /* + * Lock USB before clearing the "ifp" pointer, to avoid + * clearing the pointer in the middle of a TAP operation: + */ + USB_BUS_LOCK(ubus); ubus->ifp = NULL; + USB_BUS_UNLOCK(ubus); bpfdetach(ifp); if_detach(ifp); if_free(ifp); diff --git a/sys/dev/usb/usb_transfer.c b/sys/dev/usb/usb_transfer.c index c5815f7ae..6c2e14400 100644 --- a/sys/dev/usb/usb_transfer.c +++ b/sys/dev/usb/usb_transfer.c @@ -2381,8 +2381,11 @@ usbd_callback_wrapper(struct usb_xfer_queue *pq) } #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); -- 2.45.0