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ipv6: Fix signed integer overflow in l2tp_ip6_sendmsg

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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 <wangyufen@huawei.com>
Link: https://lore.kernel.org/r/20220607120028.845916-2-wangyufen@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Wang Yufen 2022-06-07 20:00:28 +08:00 committed by Jakub Kicinski
parent f93431c86b
commit f638a84afe
1 changed files with 3 additions and 2 deletions
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5
net/l2tp/l2tp_ip6.c
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@ -504,14 +504,15 @@ 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)