4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jens Axboe axboe@kernel.dk
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@vger.kernel.org Reported-by: syzbot syzbot+25dbecbec1e62c6b0dd4@syzkaller.appspotmail.com Reviewed-by: Josef Bacik josef@toxicpanda.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/block/nbd.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -1228,6 +1228,9 @@ 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;