Re: [PATCH v3] pxa2xx_spi: fix memory corruption

[Vasily Khoruzhick <anarsoul-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Mon, 2011-07-18 at 10:56 +0300, Vasily Khoruzhick wrote:
> On Friday 15 July 2011 05:53:31 Grant Likely wrote:
> > On Sun, Jul 10, 2011 at 06:18:19PM +0300, Vasily Khoruzhick wrote:
> > > pxa2xx_spi_probe allocates struct driver_data and null_dma_buf
> > > at same time via spi_alloc_master(), but then calculates
> > > null_dma_buf pointer incorrectly, and it causes memory corruption
> > > later if DMA usage is enabled.
> > > 
> > > Signed-off-by: Vasily Khoruzhick <anarsoul-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> > > ---
> > > v2: - add u8 __null_dma_buf[16] to the end of driver_data structure
> > > 
> > >     and use it as null_dma_buf after alignment.
> > >     - use PTR_ALIGN instead of ALIGN
> > > 
> > > v3: - drop (u8 *) cast, use & operator instead, change array name
> > > 
> > >  drivers/spi/pxa2xx_spi.c |    9 +++++----
> > >  1 files changed, 5 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/drivers/spi/pxa2xx_spi.c b/drivers/spi/pxa2xx_spi.c
> > > index dc25bee..b25fe27 100644
> > > --- a/drivers/spi/pxa2xx_spi.c
> > > +++ b/drivers/spi/pxa2xx_spi.c
> > > @@ -106,6 +106,7 @@ struct driver_data {
> > > 
> > >  	int rx_channel;
> > >  	int tx_channel;
> > >  	u32 *null_dma_buf;
> > > 
> > > +	u8 null_dma_buf_unaligned[16];
> > 
> > Don't dma buffers need to be cache-line aligned? 
> 
> No, on PXA2xx they need to be 8-bytes aligned (according to PXA27x developer's 
> manual)
> 
> > How large is the actual transfer?
> 
> Looks like 8 bytes, but I'm not sure, I'm not author of driver and did not dig 
> deeply into its code. Just attempting to fix memory corruption.
> 
> > Using the __aligned() or __cacheline_aligned
> > attribute is the correct way to make sure you've got a data buffer
> > that can be used for DMA mixed with other stuff.  Then you don't need
> > to fool around with PTR_ALIGN or anything.
> 
> Errr, it can't be applied to struct field, right? But driver needs per-device 
> null_dma_buf (there's 3 SPI controllers on PXA2xx)
> 
> > g.
> 
> Regards
> Vasily

So, any chance to see this patch merged?

Regards
Vasily


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