4.18-stable review patch.  If anyone has any objections, please let me know.

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

From: Mikulas Patocka <[email protected]>

commit bc9e9cf0401f18e33b78d4c8a518661b8346baf7 upstream.

dm-crypt should only increase device limits, it should not decrease them.

This fixes a bug where the user could creates a crypt device with 1024
sector size on the top of scsi device that had 4096 logical block size.
The limit 4096 would be lost and the user could incorrectly send
1024-I/Os to the crypt device.

Cc: [email protected]
Signed-off-by: Mikulas Patocka <[email protected]>
Signed-off-by: Mike Snitzer <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 drivers/md/dm-crypt.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -3069,11 +3069,11 @@ static void crypt_io_hints(struct dm_tar
         */
        limits->max_segment_size = PAGE_SIZE;
 
-       if (cc->sector_size != (1 << SECTOR_SHIFT)) {
-               limits->logical_block_size = cc->sector_size;
-               limits->physical_block_size = cc->sector_size;
-               blk_limits_io_min(limits, cc->sector_size);
-       }
+       limits->logical_block_size =
+               max_t(unsigned short, limits->logical_block_size, 
cc->sector_size);
+       limits->physical_block_size =
+               max_t(unsigned, limits->physical_block_size, cc->sector_size);
+       limits->io_min = max_t(unsigned, limits->io_min, cc->sector_size);
 }
 
 static struct target_type crypt_target = {


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