[PATCH] ARM: pxa: Fix pxa3xx-u2d crash when ULPI not used

[Marek Vasut]

Dne Ne 5. září 2010 10:16:48 Igor Grinberg napsal(a):
>  On 09/05/10 11:01, Marek Vasut wrote:
> > 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).
> 
> How, can it happen, that "pxa3xx-u2d driver isn't loaded at all"?
> This can happen only if you rip out the device registration or hack a
> Makefile. I don't see any other way... is there?

If you don't call pxa3xx_set_u2d_info() ?
> 
> > 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();