linux-kernel - [PATCH v2] USB: EHCI: fix dereference of ERR

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Date:	Wed, 16 Sep 2015 21:52:39 +0530
From:	Sudip Mukherjee <sudipm.mukherjee@...il.com>
To:	Alan Stern <stern@...land.harvard.edu>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	Fabio Estevam <festevam@...il.com>,
	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
	Sudip Mukherjee <sudipm.mukherjee@...il.com>
Subject: [PATCH v2] USB: EHCI: fix dereference of ERR_PTR

On error find_tt() returns either a NULL pointer or the error value in
ERR_PTR. But we were dereferencing it directly without even checking if
find_tt() returned a valid pointer or not.

Signed-off-by: Sudip Mukherjee <sudip@...torindia.org>
---

v2: used IS_ERR_OR_NULL (didn't know it was there. thanks)


 drivers/usb/host/ehci-sched.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index f9a3327..de75343 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -257,6 +257,8 @@ static void reserve_release_intr_bandwidth(struct ehci_hcd *ehci,
 	/* FS/LS bus bandwidth */
 	if (tt_usecs) {
 		tt = find_tt(qh->ps.udev);
+		if (IS_ERR_OR_NULL(tt))
+			return;
 		if (sign > 0)
 			list_add_tail(&qh->ps.ps_list, &tt->ps_list);
 		else
@@ -1373,6 +1375,8 @@ static void reserve_release_iso_bandwidth(struct ehci_hcd *ehci,
 		}
 
 		tt = find_tt(stream->ps.udev);
+		if (IS_ERR_OR_NULL(tt))
+			return;
 		if (sign > 0)
 			list_add_tail(&stream->ps.ps_list, &tt->ps_list);
 		else
-- 
1.9.1

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