4.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jens Axboe <ax...@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: sta...@vger.kernel.org
Reported-by: syzbot <syzbot+25dbecbec1e62c6b0...@syzkaller.appspotmail.com>
Reviewed-by: Josef Bacik <jo...@toxicpanda.com>
Signed-off-by: Jens Axboe <ax...@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
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;
