2014-06-17 14:18:30

by Tuomas Tynkkynen

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Subject: [PATCH] USB: EHCI: tegra: Fix use-after-free in .remove()

The tegra_ehci_hcd structure is located in the private space allocated
by the core USB code so it must not be accessed after the HCD is
freed.

Signed-off-by: Tuomas Tynkkynen <[email protected]>
---
drivers/usb/host/ehci-tegra.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/ehci-tegra.c b/drivers/usb/host/ehci-tegra.c
index 6fdcb8a..5590567 100644
--- a/drivers/usb/host/ehci-tegra.c
+++ b/drivers/usb/host/ehci-tegra.c
@@ -479,10 +479,11 @@ static int tegra_ehci_remove(struct platform_device *pdev)

usb_phy_shutdown(hcd->phy);
usb_remove_hcd(hcd);
- usb_put_hcd(hcd);

clk_disable_unprepare(tegra->clk);

+ usb_put_hcd(hcd);
+
return 0;
}

--
1.8.1.5


2014-06-17 14:26:13

by Alan Stern

[permalink] [raw]
Subject: Re: [PATCH] USB: EHCI: tegra: Fix use-after-free in .remove()

On Tue, 17 Jun 2014, Tuomas Tynkkynen wrote:

> The tegra_ehci_hcd structure is located in the private space allocated
> by the core USB code so it must not be accessed after the HCD is
> freed.
>
> Signed-off-by: Tuomas Tynkkynen <[email protected]>
> ---
> drivers/usb/host/ehci-tegra.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/host/ehci-tegra.c b/drivers/usb/host/ehci-tegra.c
> index 6fdcb8a..5590567 100644
> --- a/drivers/usb/host/ehci-tegra.c
> +++ b/drivers/usb/host/ehci-tegra.c
> @@ -479,10 +479,11 @@ static int tegra_ehci_remove(struct platform_device *pdev)
>
> usb_phy_shutdown(hcd->phy);
> usb_remove_hcd(hcd);
> - usb_put_hcd(hcd);
>
> clk_disable_unprepare(tegra->clk);
>
> + usb_put_hcd(hcd);
> +
> return 0;
> }

Acked-by: Alan Stern <[email protected]>

2014-06-17 15:56:54

by Stephen Warren

[permalink] [raw]
Subject: Re: [PATCH] USB: EHCI: tegra: Fix use-after-free in .remove()

On 06/17/2014 08:17 AM, Tuomas Tynkkynen wrote:
> The tegra_ehci_hcd structure is located in the private space allocated
> by the core USB code so it must not be accessed after the HCD is
> freed.

> diff --git a/drivers/usb/host/ehci-tegra.c b/drivers/usb/host/ehci-tegra.c

This seems to be a persistent problem. Witness commit ecc8a0cdca18 "usb:
host: tegra: fix warning messages in ehci_remove". So, I wonder if ...

> @@ -479,10 +479,11 @@ static int tegra_ehci_remove(struct platform_device *pdev)
>
> usb_phy_shutdown(hcd->phy);
> usb_remove_hcd(hcd);
> - usb_put_hcd(hcd);
>
> clk_disable_unprepare(tegra->clk);
>

It's worth putting a comment here:

/* This must be last, since *tegra is part of *hcd */
> + usb_put_hcd(hcd);
> +
> return 0;
> }

Of course, that could be a separate commit if you want.

2014-06-17 19:30:37

by Alan Stern

[permalink] [raw]
Subject: Re: [PATCH] USB: EHCI: tegra: Fix use-after-free in .remove()

On Tue, 17 Jun 2014, Stephen Warren wrote:

> On 06/17/2014 08:17 AM, Tuomas Tynkkynen wrote:
> > The tegra_ehci_hcd structure is located in the private space allocated
> > by the core USB code so it must not be accessed after the HCD is
> > freed.
>
> > diff --git a/drivers/usb/host/ehci-tegra.c b/drivers/usb/host/ehci-tegra.c
>
> This seems to be a persistent problem. Witness commit ecc8a0cdca18 "usb:
> host: tegra: fix warning messages in ehci_remove". So, I wonder if ...
>
> > @@ -479,10 +479,11 @@ static int tegra_ehci_remove(struct platform_device *pdev)
> >
> > usb_phy_shutdown(hcd->phy);
> > usb_remove_hcd(hcd);
> > - usb_put_hcd(hcd);
> >
> > clk_disable_unprepare(tegra->clk);
> >
>
> It's worth putting a comment here:
>
> /* This must be last, since *tegra is part of *hcd */
> > + usb_put_hcd(hcd);
> > +
> > return 0;
> > }

Well, maybe. At this stage it's not too likely that anything will be
added after the usb_put_hcd().

> Of course, that could be a separate commit if you want.

This affects more than ehci-tegra. The same concept applies to all the
EHCI and OHCI platform drivers that use the platform-private area.

Alan Stern