diff mbox series

[5.4,030/177] dm snapshot: properly fix a crash when an origin has no snapshots

Message ID 20210531130648.958720109@linuxfoundation.org
State Superseded
Headers show
Series None | expand

Commit Message

Greg KH May 31, 2021, 1:13 p.m. UTC 
From: Mikulas Patocka <mpatocka@redhat.com>

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 <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/md/dm-snap.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -854,7 +854,7 @@  static int dm_add_exception(void *contex
 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)