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usb: dwc2: host: Avoid use of chan->qh after qh freed 

When poking around with USB devices with slub_debug enabled, I found
another obvious use after free.  Turns out that in dwc2_hc_n_intr() I
was in a state when the contents of chan->qh was filled with 0x6b,
indicating that chan->qh was freed but chan still had a reference to
it.

Let's make sure that whenever we free qh we also make sure we remove a
reference from its channel.

The bug fixed here doesn't appear to be new--I believe I just got lucky
and happened to see it while stress testing.

Acked-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
This commit is contained in:
Douglas Anderson 2016-01-28 18:19:55 -08:00 committed by Felipe Balbi
parent 098c1ef8fe
commit 16e8021881
2 changed files with 20 additions and 0 deletions
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10
drivers/usb/dwc2/hcd.c
View File

@ -164,6 +164,9 @@ static void dwc2_qh_list_free(struct dwc2_hsotg *hsotg,
qtd_list_entry)
dwc2_hcd_qtd_unlink_and_free(hsotg, qtd, qh);
if (qh->channel && qh->channel->qh == qh)
qh->channel->qh = NULL;
spin_unlock_irqrestore(&hsotg->lock, flags);
dwc2_hcd_qh_free(hsotg, qh);
spin_lock_irqsave(&hsotg->lock, flags);
@ -554,7 +557,12 @@ static int dwc2_hcd_endpoint_disable(struct dwc2_hsotg *hsotg,
dwc2_hcd_qtd_unlink_and_free(hsotg, qtd, qh);
ep->hcpriv = NULL;
if (qh->channel && qh->channel->qh == qh)
qh->channel->qh = NULL;
spin_unlock_irqrestore(&hsotg->lock, flags);
dwc2_hcd_qh_free(hsotg, qh);
return 0;
@ -2782,6 +2790,8 @@ static int _dwc2_hcd_urb_enqueue(struct usb_hcd *hcd, struct urb *urb,
fail3:
dwc2_urb->priv = NULL;
usb_hcd_unlink_urb_from_ep(hcd, urb);
if (qh_allocated && qh->channel && qh->channel->qh == qh)
qh->channel->qh = NULL;
fail2:
spin_unlock_irqrestore(&hsotg->lock, flags);
urb->hcpriv = NULL;

10
drivers/usb/dwc2/hcd_intr.c
View File

@ -1943,6 +1943,16 @@ static void dwc2_hc_n_intr(struct dwc2_hsotg *hsotg, int chnum)
}
dwc2_writel(hcint, hsotg->regs + HCINT(chnum));
/*
* If we got an interrupt after someone called
* dwc2_hcd_endpoint_disable() we don't want to crash below
*/
if (!chan->qh) {
dev_warn(hsotg->dev, "Interrupt on disabled channel\n");
return;
}
chan->hcint = hcint;
hcint &= hcintmsk;