md: avoid overflow in raid0 calculation with large components
If a raid0 has a component device larger than 4TB, and is accessed on a 32bit
machines, then as 'chunk' is unsigned long,
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@endace.com>
Signed-off-by: Neil Brown <neilb@suse.de>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index dfe3214..2c404f7 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -415,7 +415,7 @@
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 @@
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)];