Commit 867e9913 authored by Wang Yufen's avatar Wang Yufen Committed by Zhengchao Shao
Browse files

ipv6: Fix signed integer overflow in l2tp_ip6_sendmsg 

stable inclusion
from stable-v4.19.249
commit 6c4e3486d21173d60925ef52e512cae727b43d30
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I970CO

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6c4e3486d21173d60925ef52e512cae727b43d30



--------------------------------

[ Upstream commit f638a84a ]

When len >= INT_MAX - transhdrlen, ulen = len + transhdrlen will be
overflow. To fix, we can follow what udpv6 does and subtract the
transhdrlen from the max.

Signed-off-by: default avatarWang Yufen <wangyufen@huawei.com>
Link: https://lore.kernel.org/r/20220607120028.845916-2-wangyufen@huawei.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarZhengchao Shao <shaozhengchao@huawei.com>
parent ce7ba9ee

net/l2tp/l2tp_ip6.c

+3 −2
Original line number Diff line number Diff line
@@ -517,14 +517,15 @@ static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) 
	struct ipcm6_cookie ipc6;

	int addr_len = msg->msg_namelen;

	int transhdrlen = 4; /* zero session-id */

	int ulen = len + transhdrlen;

	int ulen;

	int err;



	/* Rough check on arithmetic overflow,

	   better check is made in ip6_append_data().

	 */

	if (len > INT_MAX)

	if (len > INT_MAX - transhdrlen)

		return -EMSGSIZE;

	ulen = len + transhdrlen;



	/* Mirror BSD error message compatibility */

	if (msg->msg_flags & MSG_OOB)