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Commit 1f314bbd authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Greg Kroah-Hartman
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dm snapshot: properly fix a crash when an origin has no snapshots 



commit 7e768532b2396bcb7fbf6f82384b85c0f1d2f197 upstream.

If an origin target has no snapshots, o->split_boundary is set to 0.
This causes BUG_ON(sectors <= 0) in block/bio.c:bio_split().

Fix this by initializing chunk_size, and in turn split_boundary, to
rounddown_pow_of_two(UINT_MAX) -- the largest power of two that fits
into "unsigned" type.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e71e366d

drivers/md/dm-snap.c

+1 −1
Original line number Diff line number Diff line
@@ -788,7 +788,7 @@ static int dm_add_exception(void *context, chunk_t old, chunk_t new) 
static uint32_t __minimum_chunk_size(struct origin *o)

{

	struct dm_snapshot *snap;

	unsigned chunk_size = 0;

	unsigned chunk_size = rounddown_pow_of_two(UINT_MAX);



	if (o)

		list_for_each_entry(snap, &o->snapshots, list)