From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

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>
Acked-by: Borislav Petkov <petkovbb@gmail.com>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Tejun Heo <htejun@gmail.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/ide/ide-cd.c |    5 +++++
 1 file changed, 5 insertions(+)

diff -puN drivers/ide/ide-cd.c~ide-avoid-dma-on-the-stack-for-req_type_ata_pc drivers/ide/ide-cd.c
--- a/drivers/ide/ide-cd.c~ide-avoid-dma-on-the-stack-for-req_type_ata_pc
+++ a/drivers/ide/ide-cd.c
@@ -1195,6 +1195,7 @@ static ide_startstop_t cdrom_do_block_pc
 		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
 		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 */
_