Commit 787f17fe authored May 23, 2007 by NeilBrown Committed by Linus Torvalds May 23, 2007

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>

parent 1dbf37e8

drivers/md/raid0.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -415,7 +415,7 @@ static int raid0_make_request (request_queue_t q, struct bio bio)
		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_queue_t q, struct bio bio)

		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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