WireGuard Archive on lore.kernel.org
 help / color / Atom feed
From: Eric Dumazet <edumazet@google.com>
To: "David S . Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
	netdev <netdev@vger.kernel.org>,
	Eric Dumazet <edumazet@google.com>,
	syzbot <syzkaller@googlegroups.com>,
	wireguard@lists.zx2c4.com
Subject: [PATCH net] wireguard: device: provide sane limits for mtu setting
Date: Thu, 13 Feb 2020 22:38:14 -0800
Message-ID: <20200214063814.229451-1-edumazet@google.com> (raw)

If wireguard device mtu is set to zero, a divide by zero
crash happens in calculate_skb_padding().

This patch provides dev->min_mtu and dev->max_mtu bounds.

Fixes: e7096c131e51 ("net: WireGuard secure network tunnel")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: wireguard@lists.zx2c4.com
---
 drivers/net/wireguard/device.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/wireguard/device.c b/drivers/net/wireguard/device.c
index 43db442b1373073eaf5e805cfe6cfee15875437a..c02b84cca122d92ee8a81c5efdcf67aada2554d6 100644
--- a/drivers/net/wireguard/device.c
+++ b/drivers/net/wireguard/device.c
@@ -271,9 +271,14 @@ static void wg_setup(struct net_device *dev)
 	dev->features |= WG_NETDEV_FEATURES;
 	dev->hw_features |= WG_NETDEV_FEATURES;
 	dev->hw_enc_features |= WG_NETDEV_FEATURES;
+
 	dev->mtu = ETH_DATA_LEN - MESSAGE_MINIMUM_LENGTH -
 		   sizeof(struct udphdr) -
 		   max(sizeof(struct ipv6hdr), sizeof(struct iphdr));
+	dev->min_mtu = MESSAGE_PADDING_MULTIPLE;
+	dev->max_mtu = ETH_MAX_MTU - MESSAGE_MINIMUM_LENGTH -
+		       sizeof(struct udphdr) -
+		       max(sizeof(struct ipv6hdr), sizeof(struct iphdr));
 
 	SET_NETDEV_DEVTYPE(dev, &device_type);
 
-- 
2.25.0.265.gbab2e86ba0-goog

_______________________________________________
WireGuard mailing list
WireGuard@lists.zx2c4.com
https://lists.zx2c4.com/mailman/listinfo/wireguard

             reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-14  6:38 Eric Dumazet [this message]
2020-02-14  6:40 ` Quan Zhou
2020-02-14  7:11   ` Samir Nassar
2020-02-14 10:11     ` Quan Zhou
2020-02-14  9:11 ` Jason A. Donenfeld

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200214063814.229451-1-edumazet@google.com \
    --to=edumazet@google.com \
    --cc=davem@davemloft.net \
    --cc=eric.dumazet@gmail.com \
    --cc=netdev@vger.kernel.org \
    --cc=syzkaller@googlegroups.com \
    --cc=wireguard@lists.zx2c4.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

WireGuard Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/wireguard/0 wireguard/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 wireguard wireguard/ https://lore.kernel.org/wireguard \
		wireguard@lists.zx2c4.com
	public-inbox-index wireguard

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/com.zx2c4.lists.wireguard


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git