Date: Sat, 15 Aug 2015 09:00:37 +0000 (UTC) From: Hans Petter Selasky <hselasky@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r286799 - head/sys/dev/usb Message-ID: <201508150900.t7F90bm4063804@repo.freebsd.org>
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Author: hselasky Date: Sat Aug 15 09:00:36 2015 New Revision: 286799 URL: https://svnweb.freebsd.org/changeset/base/286799 Log: 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. MFC after: 2 weeks Modified: head/sys/dev/usb/usb_pf.c head/sys/dev/usb/usb_transfer.c Modified: head/sys/dev/usb/usb_pf.c ============================================================================== --- head/sys/dev/usb/usb_pf.c Sat Aug 15 08:42:33 2015 (r286798) +++ head/sys/dev/usb/usb_pf.c Sat Aug 15 09:00:36 2015 (r286799) @@ -221,7 +221,13 @@ usbpf_clone_destroy(struct if_clone *ifc 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); Modified: head/sys/dev/usb/usb_transfer.c ============================================================================== --- head/sys/dev/usb/usb_transfer.c Sat Aug 15 08:42:33 2015 (r286798) +++ head/sys/dev/usb/usb_transfer.c Sat Aug 15 09:00:36 2015 (r286799) @@ -2398,8 +2398,11 @@ 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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