4.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jens Axboe <axboe@xxxxxxxxx> commit bc811f05d77f47059c197a98b6ad242eb03999cb upstream. syzbot reports a divide-by-zero off the NBD_SET_BLKSIZE ioctl. We need proper validation of the input here. Not just if it's zero, but also if the value is a power-of-2 and in a valid range. Add that. Cc: stable@xxxxxxxxxxxxxxx Reported-by: syzbot <syzbot+25dbecbec1e62c6b0dd4@xxxxxxxxxxxxxxxxxxxxxxxxx> Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/block/nbd.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -1239,6 +1239,9 @@ static int __nbd_ioctl(struct block_devi case NBD_SET_SOCK: return nbd_add_socket(nbd, arg, false); case NBD_SET_BLKSIZE: + if (!arg || !is_power_of_2(arg) || arg < 512 || + arg > PAGE_SIZE) + return -EINVAL; nbd_size_set(nbd, arg, div_s64(config->bytesize, arg)); return 0;
