From: Martijn Coenen <maco@xxxxxxxxxxx> commit 79e5dc59e2974a48764269fa9ff544ae8ffe3338 upstream. The device size calculation was done before processing the loop configuration, which meant that the we set the size on the underlying block device incorrectly in case lo_offset/lo_sizelimit were set in the configuration. Delay computing the size until we've setup the device parameters correctly. Fixes: 3448914e8cc5("loop: Add LOOP_CONFIGURE ioctl") Reported-by: Lennart Poettering <mzxreary@xxxxxxxxxxx> Tested-by: Yang Xu <xuyang2018.jy@xxxxxxxxxxxxxx> Signed-off-by: Martijn Coenen <maco@xxxxxxxxxxx> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/block/loop.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1114,8 +1114,6 @@ static int loop_configure(struct loop_de mapping = file->f_mapping; inode = mapping->host; - size = get_loop_size(lo, file); - if ((config->info.lo_flags & ~LOOP_CONFIGURE_SETTABLE_FLAGS) != 0) { error = -EINVAL; goto out_unlock; @@ -1165,6 +1163,8 @@ static int loop_configure(struct loop_de loop_update_rotational(lo); loop_update_dio(lo); loop_sysfs_init(lo); + + size = get_loop_size(lo, file); loop_set_size(lo, size); set_blocksize(bdev, S_ISBLK(inode->i_mode) ?