netdev - [PATCH net-next] ipv6: Fix signed integer overflow in __ip6_append

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Message-ID: <20220524034629.395939-1-wangyufen@huawei.com>
Date:   Tue, 24 May 2022 11:46:29 +0800
From:   Wang Yufen <wangyufen@...wei.com>
To:     <davem@...emloft.net>, <yoshfuji@...ux-ipv6.org>,
        <dsahern@...nel.org>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <ast@...nel.org>, <daniel@...earbox.net>,
        <andrii@...nel.org>, <kafai@...com>, <songliubraving@...com>,
        <yhs@...com>, <john.fastabend@...il.com>, <kpsingh@...nel.org>
CC:     <netdev@...r.kernel.org>, <bpf@...r.kernel.org>
Subject: [PATCH net-next] ipv6: Fix signed integer overflow in __ip6_append_data

Resurrect ubsan overflow checks and ubsan report this warning,
fix it by change len check from INT_MAX to IPV6_MAXPLEN.

UBSAN: signed-integer-overflow in net/ipv6/ip6_output.c:1489:19
2147479552 + 8567 cannot be represented in type 'int'
CPU: 0 PID: 253 Comm: err Not tainted 5.16.0+ #1
Hardware name: linux,dummy-virt (DT)
Call trace:
  dump_backtrace+0x214/0x230
  show_stack+0x30/0x78
  dump_stack_lvl+0xf8/0x118
  dump_stack+0x18/0x30
  ubsan_epilogue+0x18/0x60
  handle_overflow+0xd0/0xf0
  __ubsan_handle_add_overflow+0x34/0x44
  __ip6_append_data.isra.48+0x1598/0x1688
  ip6_append_data+0x128/0x260
  udpv6_sendmsg+0x680/0xdd0
  inet6_sendmsg+0x54/0x90
  sock_sendmsg+0x70/0x88
  ____sys_sendmsg+0xe8/0x368
  ___sys_sendmsg+0x98/0xe0
  __sys_sendmmsg+0xf4/0x3b8
  __arm64_sys_sendmmsg+0x34/0x48
  invoke_syscall+0x64/0x160
  el0_svc_common.constprop.4+0x124/0x300
  do_el0_svc+0x44/0xc8
  el0_svc+0x3c/0x1e8
  el0t_64_sync_handler+0x88/0xb0
  el0t_64_sync+0x16c/0x170

Reported-by: Hulk Robot <hulkci@...wei.com>
Signed-off-by: Wang Yufen <wangyufen@...wei.com>
---
 net/ipv6/udp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 7f0fa9bd9ffe..9cdb8c5f734c 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1368,7 +1368,7 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	/* Rough check on arithmetic overflow,
 	   better check is made in ip6_append_data().
 	   */
-	if (len > INT_MAX - sizeof(struct udphdr))
+	if (len > IPV6_MAXPLEN)
 		return -EMSGSIZE;
 
 	getfrag  =  is_udplite ?  udplite_getfrag : ip_generic_getfrag;
-- 
2.25.1