From bc811f05d77f47059c197a98b6ad242eb03999cb Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Tue, 4 Sep 2018 11:52:34 -0600
Subject: [PATCH] nbd: don't allow invalid blocksize settings
Git-commit: bc811f05d77f47059c197a98b6ad242eb03999cb
References: Git-fixes
Patch-mainline: v4.19-rc3
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>
Acked-by: Coly Li <colyli@suse.de>
---
drivers/block/nbd.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 3863c00372bb..14a51254c3db 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1239,6 +1239,9 @@ 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;
--
2.16.4