From 7ee06ddc4038f936b0d4459d37a7d4d844fb03db Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Fri, 7 May 2021 11:38:10 -0400 Subject: [PATCH] dm snapshot: fix a crash when an origin has no snapshots 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. Reported-by: Michael Tokarev Tested-by: Michael Tokarev Cc: stable@vger.kernel.org Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer --- drivers/md/dm-snap.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index a2acb01..2a51ddd 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -855,12 +855,11 @@ 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) - chunk_size = min_not_zero(chunk_size, - snap->store->chunk_size); + chunk_size = min(chunk_size, snap->store->chunk_size); return (uint32_t) chunk_size; } -- 2.7.4