The devices with size >= 2^63 bytes can't be used reliably by userspace because the type off_t is a signed 64-bit integer. Therefore, we limit the maximum size of a device mapper device to 2^63-512 bytes. Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> --- drivers/md/dm-table.c | 4 ++++ 1 file changed, 4 insertions(+) Index: linux-2.6/drivers/md/dm-table.c =================================================================== --- linux-2.6.orig/drivers/md/dm-table.c 2025-02-24 12:41:49.000000000 +0100 +++ linux-2.6/drivers/md/dm-table.c 2025-03-14 13:42:13.000000000 +0100 @@ -697,6 +697,10 @@ int dm_table_add_target(struct dm_table DMERR("%s: zero-length target", dm_device_name(t->md)); return -EINVAL; } + if (start + len < start || start + len > LLONG_MAX >> SECTOR_SHIFT) { + DMERR("%s: too large device", dm_device_name(t->md)); + return -EINVAL; + } ti->type = dm_get_target_type(type); if (!ti->type) {