From: Mikulas Patocka Date: Tue, 25 May 2021 17:17:19 +0000 (-0400) Subject: dm snapshot: properly fix a crash when an origin has no snapshots X-Git-Tag: v4.4.271~49 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=eb787192910ee8fca9764c376f392e0ab69de58e;p=thirdparty%2Fkernel%2Fstable.git 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: Mikulas Patocka Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index 2a1a7025b4b92..cbd3dbfad7d14 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -789,7 +789,7 @@ 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)