On Tue, 03 Jun 2008 14:55:17 -0700 akpm@xxxxxxxxxxxxxxxxxxxx wrote: > > The patch titled > ide: avoid DMA on the stack for REQ_TYPE_ATA_PC > has been added to the -mm tree. Its filename is > ide-avoid-dma-on-the-stack-for-req_type_ata_pc.patch > > Before you just go and hit "reply", please: > a) Consider who else should be cc'ed > b) Prefer to cc a suitable mailing list as well > c) Ideally: find the original patch on the mailing list and do a > reply-to-all to that, adding suitable additional cc's > > *** Remember to use Documentation/SubmitChecklist when testing your code *** > > See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find > out what to do about this > > The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ > > ------------------------------------------------------ > Subject: ide: avoid DMA on the stack for REQ_TYPE_ATA_PC > From: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx> > > 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@xxxxxxxxxxxxx> > Acked-by: Borislav Petkov <petkovbb@xxxxxxxxx> > Cc: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx> > Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx> > Cc: Tejun Heo <htejun@xxxxxxxxx> > Cc: Jens Axboe <jens.axboe@xxxxxxxxxx> > Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > --- > > 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 */ Here's an updated version. A helper function to test if an object is on the stack was added to -mm. We can use it to simplify this patch. http://marc.info/?l=linux-kernel&m=121315043731994&w=2 = From: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx> Subject: [PATCH] ide: avoid DMA on the stack for REQ_TYPE_ATA_PC 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@xxxxxxxxxxxxx> --- drivers/ide/ide-cd.c | 9 +++++---- 1 files changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c index e3f085c..f3a4442 100644 --- a/drivers/ide/ide-cd.c +++ b/drivers/ide/ide-cd.c @@ -1194,12 +1194,12 @@ static ide_startstop_t cdrom_do_block_pc(ide_drive_t *drive, struct request *rq) if (rq->bio || ((rq->cmd_type == REQ_TYPE_ATA_PC) && rq->data_len)) { struct request_queue *q = drive->queue; unsigned int alignment; - unsigned long addr; + char *buf; if (rq->bio) - addr = (unsigned long)bio_data(rq->bio); + buf = bio_data(rq->bio); else - addr = (unsigned long)rq->data; + buf = rq->data; info->dma = drive->using_dma; @@ -1210,7 +1210,8 @@ static ide_startstop_t cdrom_do_block_pc(ide_drive_t *drive, struct request *rq) * separate masks. */ alignment = queue_dma_alignment(q) | q->dma_pad_mask; - if (addr & alignment || rq->data_len & alignment) + if ((unsigned long)buf & alignment || rq->data_len & alignment + || object_is_on_stack(buf)) info->dma = 0; } -- 1.5.5.GIT -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
