From: visa <visa@openbsd.org>
Date: Tue, 20 Jun 2017 15:49:00 +0000 (+0000)
Subject: Check the validity of the `qtd' pointer after each interrupt case
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=bd38a9bdcd5e888bff7de4d3a7713580f6a52c14;p=openbsd

Check the validity of the `qtd' pointer after each interrupt case
and bail out if the pointer has become invalid. This prevents
use-after-free memory accesses that corrupted the dwc2qtd pool.

This fix improves stability on the Raspberry Pi 3.

From Linux commit dc8730846948e517169f630826cd2c97615f5ee8
OK kettenis@
---

diff --git a/sys/dev/usb/dwc2/dwc2_hcdintr.c b/sys/dev/usb/dwc2/dwc2_hcdintr.c
index 34a0d9d5cd2..3735c811838 100644
--- a/sys/dev/usb/dwc2/dwc2_hcdintr.c
+++ b/sys/dev/usb/dwc2/dwc2_hcdintr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dwc2_hcdintr.c,v 1.7 2017/02/12 17:41:17 visa Exp $	*/
+/*	$OpenBSD: dwc2_hcdintr.c,v 1.8 2017/06/20 15:49:00 visa Exp $	*/
 /*	$NetBSD: dwc2_hcdintr.c,v 1.11 2014/11/24 10:14:14 skrll Exp $	*/
 
 /*
@@ -1951,6 +1951,20 @@ STATIC void dwc2_hc_chhltd_intr(struct dwc2_hsotg *hsotg,
 	}
 }
 
+/*
+ * Check if the given qtd is still the top of the list (and thus valid).
+ *
+ * If dwc2_hcd_qtd_unlink_and_free() has been called since we grabbed
+ * the qtd from the top of the list, this will return false (otherwise true).
+ */
+STATIC bool dwc2_check_qtd_still_ok(struct dwc2_qtd *qtd, struct dwc2_qh *qh)
+{
+	if (!qh)
+		return false;
+
+	return (TAILQ_FIRST(&qh->qtd_list) == qtd);
+}
+
 /* Handles interrupt for a specific Host Channel */
 STATIC void dwc2_hc_n_intr(struct dwc2_hsotg *hsotg, int chnum)
 {
@@ -2032,27 +2046,59 @@ STATIC void dwc2_hc_n_intr(struct dwc2_hsotg *hsotg, int chnum)
 		 */
 		hcint &= ~HCINTMSK_NYET;
 	}
-	if (hcint & HCINTMSK_CHHLTD)
+
+	if (hcint & HCINTMSK_CHHLTD) {
 		dwc2_hc_chhltd_intr(hsotg, chan, chnum, qtd);
-	if (hcint & HCINTMSK_AHBERR)
+		if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
+			goto exit;
+	}
+	if (hcint & HCINTMSK_AHBERR) {
 		dwc2_hc_ahberr_intr(hsotg, chan, chnum, qtd);
-	if (hcint & HCINTMSK_STALL)
+		if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
+			goto exit;
+	}
+	if (hcint & HCINTMSK_STALL) {
 		dwc2_hc_stall_intr(hsotg, chan, chnum, qtd);
-	if (hcint & HCINTMSK_NAK)
+		if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
+			goto exit;
+	}
+	if (hcint & HCINTMSK_NAK) {
 		dwc2_hc_nak_intr(hsotg, chan, chnum, qtd);
-	if (hcint & HCINTMSK_ACK)
+		if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
+			goto exit;
+	}
+	if (hcint & HCINTMSK_ACK) {
 		dwc2_hc_ack_intr(hsotg, chan, chnum, qtd);
-	if (hcint & HCINTMSK_NYET)
+		if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
+			goto exit;
+	}
+	if (hcint & HCINTMSK_NYET) {
 		dwc2_hc_nyet_intr(hsotg, chan, chnum, qtd);
-	if (hcint & HCINTMSK_XACTERR)
+		if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
+			goto exit;
+	}
+	if (hcint & HCINTMSK_XACTERR) {
 		dwc2_hc_xacterr_intr(hsotg, chan, chnum, qtd);
-	if (hcint & HCINTMSK_BBLERR)
+		if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
+			goto exit;
+	}
+	if (hcint & HCINTMSK_BBLERR) {
 		dwc2_hc_babble_intr(hsotg, chan, chnum, qtd);
-	if (hcint & HCINTMSK_FRMOVRUN)
+		if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
+			goto exit;
+	}
+	if (hcint & HCINTMSK_FRMOVRUN) {
 		dwc2_hc_frmovrun_intr(hsotg, chan, chnum, qtd);
-	if (hcint & HCINTMSK_DATATGLERR)
+		if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
+			goto exit;
+	}
+	if (hcint & HCINTMSK_DATATGLERR) {
 		dwc2_hc_datatglerr_intr(hsotg, chan, chnum, qtd);
+		if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
+			goto exit;
+	}
 
+exit:
 	chan->hcint = 0;
 }