Re: [PATCH v2 -mm 4/6] ide: avoid DMA on the stack for REQ_TYPE_ATA_PC

[Borislav Petkov <petkovbb@googlemail.com>]

On Mon, Jun 02, 2008 at 03:57:30PM +0900, FUJITA Tomonori wrote:
> Some REQ_TYPE_ATA_PC commands uses the stack buffers for DMA, which
> leads to memory corruption on a non-coherent platform.
> 
> With regard to alignment and padding, ide-cd has the the dma safe
> check for sg requests and REQ_TYPE_ATA_PC. This adds the stack buffer
> check to that check.
> 
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
> Cc: Borislav Petkov <petkovbb@gmail.com>
> Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
> ---
>  drivers/ide/ide-cd.c |    5 +++++
>  1 files changed, 5 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
> index e3f085c..e12d602 100644
> --- a/drivers/ide/ide-cd.c
> +++ b/drivers/ide/ide-cd.c
> @@ -1195,6 +1195,7 @@ static ide_startstop_t cdrom_do_block_pc(ide_drive_t *drive, struct request *rq)
>  		struct request_queue *q = drive->queue;
>  		unsigned int alignment;
>  		unsigned long addr;
> +		unsigned long stack_mask = ~(THREAD_SIZE - 1);
>  
>  		if (rq->bio)
>  			addr = (unsigned long)bio_data(rq->bio);
> @@ -1212,6 +1213,10 @@ static ide_startstop_t cdrom_do_block_pc(ide_drive_t *drive, struct request *rq)
>  		alignment = queue_dma_alignment(q) | q->dma_pad_mask;
>  		if (addr & alignment || rq->data_len & alignment)
>  			info->dma = 0;
> +
> +		if (!((addr & stack_mask) ^
> +		      ((unsigned long)current->stack & stack_mask)))
> +			info->dma = 0;
>  	}
>  
>  	/* start sending the command to the drive */
> -- 
> 1.5.4.2

Looks good, thanks.

Acked-by: Borislav Petkov <petkovbb@gmail.com>

-- 
Regards/Gruß,
    Boris.
--
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html