[patch 05/54] md: Avoid overflow in raid0 calculation with large components.

From: Chris Wright
Date: Fri Jun 08 2007 - 03:36:49 EST

-stable review patch. If anyone has any objections, please let us know.

From: NeilBrown <neilb@xxxxxxx>

If a raid0 has a component device larger than 4TB, and is accessed on
a 32bit machines, then as 'chunk' is unsigned lock,
chunk << chunksize_bits
can overflow (this can be as high as the size of the device in KB).
chunk itself will not overflow (without triggering a BUG).

So change 'chunk' to be 'sector_t, and get rid of the 'BUG' as it becomes
impossible to hit.

Cc: "Jeff Zheng" <Jeff.Zheng@xxxxxxxxxx>
Signed-off-by: Neil Brown <neilb@xxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

drivers/md/raid0.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff .prev/drivers/md/raid0.c ./drivers/md/raid0.c
--- linux-
+++ linux-
@@ -415,7 +415,7 @@ static int raid0_make_request (request_q
raid0_conf_t *conf = mddev_to_conf(mddev);
struct strip_zone *zone;
mdk_rdev_t *tmp_dev;
- unsigned long chunk;
+ sector_t chunk;
sector_t block, rsect;
const int rw = bio_data_dir(bio);

@@ -470,7 +470,6 @@ static int raid0_make_request (request_q

sector_div(x, zone->nb_dev);
chunk = x;
- BUG_ON(x != (sector_t)chunk);

x = block >> chunksize_bits;
tmp_dev = zone->dev[sector_div(x, zone->nb_dev)];

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