From 23ecbbad7bf921f83a5c99718ded203676ddd91c Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 4 Sep 2018 11:52:34 -0600 Subject: nbd: don't allow invalid blocksize settings 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 Reviewed-by: Josef Bacik Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- drivers/block/nbd.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/block/nbd.c') diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 5e55d03d3d01..fe1414df0f33 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -1228,6 +1228,9 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd, 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; -- cgit v1.2.3