[PATCH 3.10 07/70] sunvdc: limit each sg segment to a page

Greg Kroah-Hartman
2014-11-19T21:14:51Z

From: Dwight Engen <dwight.engen@oracle.com>

[ Upstream commit 5eed69ffd248c9f68f56c710caf07db134aef28b ]

ldc_map_sg() could fail its check that the number of pages referred to
by the sg scatterlist was <= the number of cookies.

This fixes the issue by doing a similar thing to the xen-blkfront driver,
ensuring that the scatterlist will only ever contain a segment count <=
port->ring_cookies, and each segment will be page aligned, and <= page
size. This ensures that the scatterlist is always mappable.

Orabug: 19347817
OraBZ: 15945

Signed-off-by: Dwight Engen <dwight.engen@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/block/sunvdc.c | 4 ++++
1 file changed, 4 insertions(+)

--- a/drivers/block/sunvdc.c
+++ b/drivers/block/sunvdc.c
@@ -747,6 +747,10 @@ static int probe_disk(struct vdc_port *p

port->disk = g;

+ /* Each segment in a request is up to an aligned page in size. */
+ blk_queue_segment_boundary(q, PAGE_SIZE - 1);
+ blk_queue_max_segment_size(q, PAGE_SIZE);
+
blk_queue_max_segments(q, port->ring_cookies);
blk_queue_max_hw_sectors(q, port->max_xfer_size);
g->major = vdc_major;