[PATCH AUTOSEL 4.19 16/18] ipv6: Fix signed integer overflow in l2tp_ip6_sendmsg
From: Sasha Levin <sashal@kernel.org>
Date: 2022-06-14 02:25:56
Also in:
lkml, stable
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From: Wang Yufen <redacted> [ Upstream commit f638a84afef3dfe10554c51820c16e39a278c915 ] 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: Wang Yufen <redacted> Link: https://lore.kernel.org/r/20220607120028.845916-2-wangyufen@huawei.com (local) Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> --- net/l2tp/l2tp_ip6.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c
index 2ff25c445b82..9dae10d8880c 100644
--- a/net/l2tp/l2tp_ip6.c
+++ b/net/l2tp/l2tp_ip6.c@@ -519,14 +519,15 @@ 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)
--
2.35.1