[PATCH] ARM: pxa: Fix pxa3xx-u2d crash when ULPI not used
Marek Vasut
marek.vasut at gmail.com
Sun Sep 5 04:01:22 EDT 2010
Dne Ne 5. září 2010 09:54:31 Igor Grinberg napsal(a):
> On 09/03/10 23:35, Marek Vasut wrote:
> > In case the pxa3xx-u2d driver isn't used, probing of ohci-pxa27x will
> > cause an ugly kernel crash (NULL pointer dereference in
> > pxa3xx_u2d_start_hc(), because struct u2d is NULL and clk_enable() call
> > will crash the kernel, trying to access it).
>
> ohci code checks for pxa3xx cpu and only then runs start/stop hc.
Exactly ... and in case "struct pxa3xx_u2d_ulpi *u2d" is NULL, clk_enable will
crash the kernel.
> pxa3xx_ulpi.c is compiled if CONFIG_PXA3xx is selected.
> The device <-> driver binding should not be a problem, so the
> pxa3xx_u2d_probe() will run.
> The only case, I see, when struct u2d does not exist is failure of the
> probe function. If this is the case, we are having an abnormal execution
> and if your patch is dealing with this issue, shouldn't you comment it as
> such?
Not at all ... if the pxa3xx-u2d driver isn't loaded at all, the function
(start/stop hc) is still called, but struct pxa3xx_u2d_ulpi *u2d is NULL. In
this case, if you call clk_enable(u2d->clk), you crash the kernel (because u2d
is NULL).
Good night, I'll be back in 8 hrs or so :)
>
> > Signed-off-by: Marek Vasut <marek.vasut at gmail.com>
> > ---
> >
> > arch/arm/mach-pxa/pxa3xx-ulpi.c | 8 ++++++++
> > 1 files changed, 8 insertions(+), 0 deletions(-)
> >
> > diff --git a/arch/arm/mach-pxa/pxa3xx-ulpi.c
> > b/arch/arm/mach-pxa/pxa3xx-ulpi.c index e57439e..ce7168b 100644
> > --- a/arch/arm/mach-pxa/pxa3xx-ulpi.c
> > +++ b/arch/arm/mach-pxa/pxa3xx-ulpi.c
> > @@ -252,6 +252,10 @@ int pxa3xx_u2d_start_hc(struct usb_bus *host)
> >
> > {
> >
> > int err = 0;
> >
> > + /* In case the PXA3xx ULPI isn't used, do nothing. */
> > + if (!u2d)
> > + return 0;
> > +
> >
> > clk_enable(u2d->clk);
> >
> > if (cpu_is_pxa310()) {
> >
> > @@ -264,6 +268,10 @@ int pxa3xx_u2d_start_hc(struct usb_bus *host)
> >
> > void pxa3xx_u2d_stop_hc(struct usb_bus *host)
> > {
> >
> > + /* In case the PXA3xx ULPI isn't used, do nothing. */
> > + if (!u2d)
> > + return;
> > +
> >
> > if (cpu_is_pxa310())
> >
> > pxa310_stop_otg_hc();
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