[PATCH 3/3] SPI: spi_sh_msiof: fix wrong address calculation, which leads to an Oops

[PATCH 3/3] SPI: spi_sh_msiof: fix wrong address calculation, which leads to an Oops

[Guennadi Liakhovetski]

NULL + <small offset> != NULL, but reading from that <small offset> address
is usually not a very good idea and often leads to problems, like kernel
Oopses in this case, easily reproducible by writing to an SD-card, used in
SPI mode.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
---
 drivers/spi/spi_sh_msiof.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi_sh_msiof.c b/drivers/spi/spi_sh_msiof.c
index 658bd05..6d30829 100644
--- a/drivers/spi/spi_sh_msiof.c
+++ b/drivers/spi/spi_sh_msiof.c
@@ -568,9 +568,11 @@ static int sh_msiof_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
 	bytes_done = 0;
 
 	while (bytes_done < t->len) {
+		void *rx_buf = t->rx_buf ? t->rx_buf + bytes_done : NULL;
+		const void *tx_buf = t->tx_buf ? t->tx_buf + bytes_done : NULL;
 		n = sh_msiof_spi_txrx_once(p, tx_fifo, rx_fifo,
-					   t->tx_buf + bytes_done,
-					   t->rx_buf + bytes_done,
+					   tx_buf,
+					   rx_buf,
 					   words, bits);
 		if (n < 0)
 			break;
-- 
1.7.2.3

Re: [PATCH 3/3] SPI: spi_sh_msiof: fix wrong address calculation, which leads to an Oops

[Grant Likely]

On Fri, Jan 21, 2011 at 04:56:47PM +0100, Guennadi Liakhovetski wrote:
> NULL + <small offset> != NULL, but reading from that <small offset> address
> is usually not a very good idea and often leads to problems, like kernel
> Oopses in this case, easily reproducible by writing to an SD-card, used in
> SPI mode.
> 
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>

Applied, thanks.  Since this is an oops fix, I'll push this one to
Linus before the next -rc.  The other two can go into linux-next for
2.6.39.

g.

> ---
>  drivers/spi/spi_sh_msiof.c |    6 ++++--
>  1 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/spi/spi_sh_msiof.c b/drivers/spi/spi_sh_msiof.c
> index 658bd05..6d30829 100644
> --- a/drivers/spi/spi_sh_msiof.c
> +++ b/drivers/spi/spi_sh_msiof.c
> @@ -568,9 +568,11 @@ static int sh_msiof_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
>  	bytes_done = 0;
>  
>  	while (bytes_done < t->len) {
> +		void *rx_buf = t->rx_buf ? t->rx_buf + bytes_done : NULL;
> +		const void *tx_buf = t->tx_buf ? t->tx_buf + bytes_done : NULL;
>  		n = sh_msiof_spi_txrx_once(p, tx_fifo, rx_fifo,
> -					   t->tx_buf + bytes_done,
> -					   t->rx_buf + bytes_done,
> +					   tx_buf,
> +					   rx_buf,
>  					   words, bits);
>  		if (n < 0)
>  			break;
> -- 
> 1.7.2.3
> 
> 
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Re: [PATCH 3/3] SPI: spi_sh_msiof: fix wrong address calculation, which leads to an Oops

[Paul Mundt]

On Fri, Jan 21, 2011 at 09:27:43AM -0700, Grant Likely wrote:
> On Fri, Jan 21, 2011 at 04:56:47PM +0100, Guennadi Liakhovetski wrote:
> > NULL + <small offset> != NULL, but reading from that <small offset> address
> > is usually not a very good idea and often leads to problems, like kernel
> > Oopses in this case, easily reproducible by writing to an SD-card, used in
> > SPI mode.
> > 
> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> 
> Applied, thanks.  Since this is an oops fix, I'll push this one to
> Linus before the next -rc.  The other two can go into linux-next for
> 2.6.39.
> 
I haven't been following too closely, but this may also be a good -stable
candidate.