loop: loop_set_status_from_info() check before assignment

mainline inclusion
from mainline-v6.3-rc1
commit 9f6ad5d5
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7JHOA
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9f6ad5d533d1c71e51bdd06a5712c4fbc8768dfa

--------------------------------

In loop_set_status_from_info(), lo->lo_offset and lo->lo_sizelimit should
be checked before reassignment, because if an overflow error occurs, the
original correct value will be changed to the wrong value, and it will not
be changed back.

More, the original patch did not solve the problem, the value was set and
ioctl returned an error, but the subsequent io used the value in the loop
driver, which still caused an alarm:

loop_handle_cmd
 do_req_filebacked
  loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
  lo_rw_aio
   cmd->iocb.ki_pos = pos
Signed-off-by: NZhong Jinghua <zhongjinghua@huawei.com>
Reviewed-by: NChaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20230221095027.3656193-1-zhongjinghua@huaweicloud.comSigned-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NZhong Jinghua <zhongjinghua@huawei.com>
Reviewed-by: NYu Kuai <yukuai3@huawei.com>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

drivers/block/loop.c

@@ -1283,13 +1283,15 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
 				lo->lo_device->bd_inode->i_mapping->nrpages);
 			goto out_unfreeze;
 		}
+
+		/* Avoid assigning overflow values */
+		if (info->lo_offset > LLONG_MAX || info->lo_sizelimit > LLONG_MAX)
+			return -EOVERFLOW;
+
 		if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit)) {
 			err = -EFBIG;
 			goto out_unfreeze;
 		}
-		/* loff_t vars have been assigned __u64 */
-		if (lo->lo_offset < 0 || lo->lo_sizelimit < 0)
-			return -EOVERFLOW;
 	}
 
 	loop_config_discard(lo);