[PATCH net-next v3] ipv6: Fix signed integer overflow in __ip6_append_data

[PATCH net-next v3] ipv6: Fix signed integer overflow in __ip6_append_data

[Wang Yufen]

Resurrect ubsan overflow checks and ubsan report this warning,
fix it by change the variable [length] type to size_t.

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

Changes since v1:
-Change the variable [length] type to unsigned, as Eric Dumazet suggested.
Changes since v2:
-Don't change exthdrlen type in ip6_make_skb, as Paolo Abeni suggested.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wang Yufen <wangyufen@huawei.com>
---
 include/net/ipv6.h    | 4 ++--
 net/ipv6/ip6_output.c | 6 +++---
 net/ipv6/udp.c        | 2 +-
 net/l2tp/l2tp_ip6.c   | 2 +-
 4 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 5b38bf1a586b..de9dcc5652c4 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -1063,7 +1063,7 @@ int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr);
 int ip6_append_data(struct sock *sk,
 		    int getfrag(void *from, char *to, int offset, int len,
 				int odd, struct sk_buff *skb),
-		    void *from, int length, int transhdrlen,
+		    void *from, size_t length, int transhdrlen,
 		    struct ipcm6_cookie *ipc6, struct flowi6 *fl6,
 		    struct rt6_info *rt, unsigned int flags);
 
@@ -1079,7 +1079,7 @@ struct sk_buff *__ip6_make_skb(struct sock *sk, struct sk_buff_head *queue,
 struct sk_buff *ip6_make_skb(struct sock *sk,
 			     int getfrag(void *from, char *to, int offset,
 					 int len, int odd, struct sk_buff *skb),
-			     void *from, int length, int transhdrlen,
+			     void *from, size_t length, int transhdrlen,
 			     struct ipcm6_cookie *ipc6,
 			     struct rt6_info *rt, unsigned int flags,
 			     struct inet_cork_full *cork);
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 4081b12a01ff..77e3f5970ce4 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1450,7 +1450,7 @@ static int __ip6_append_data(struct sock *sk,
 			     struct page_frag *pfrag,
 			     int getfrag(void *from, char *to, int offset,
 					 int len, int odd, struct sk_buff *skb),
-			     void *from, int length, int transhdrlen,
+			     void *from, size_t length, int transhdrlen,
 			     unsigned int flags, struct ipcm6_cookie *ipc6)
 {
 	struct sk_buff *skb, *skb_prev = NULL;
@@ -1798,7 +1798,7 @@ static int __ip6_append_data(struct sock *sk,
 int ip6_append_data(struct sock *sk,
 		    int getfrag(void *from, char *to, int offset, int len,
 				int odd, struct sk_buff *skb),
-		    void *from, int length, int transhdrlen,
+		    void *from, size_t length, int transhdrlen,
 		    struct ipcm6_cookie *ipc6, struct flowi6 *fl6,
 		    struct rt6_info *rt, unsigned int flags)
 {
@@ -1995,7 +1995,7 @@ EXPORT_SYMBOL_GPL(ip6_flush_pending_frames);
 struct sk_buff *ip6_make_skb(struct sock *sk,
 			     int getfrag(void *from, char *to, int offset,
 					 int len, int odd, struct sk_buff *skb),
-			     void *from, int length, int transhdrlen,
+			     void *from, size_t length, int transhdrlen,
 			     struct ipcm6_cookie *ipc6, struct rt6_info *rt,
 			     unsigned int flags, struct inet_cork_full *cork)
 {
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 55afd7f39c04..91704bbc7715 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1308,7 +1308,7 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	struct ipcm6_cookie ipc6;
 	int addr_len = msg->msg_namelen;
 	bool connected = false;
-	int ulen = len;
+	size_t ulen = len;
 	int corkreq = READ_ONCE(up->corkflag) || msg->msg_flags&MSG_MORE;
 	int err;
 	int is_udplite = IS_UDPLITE(sk);
diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c
index c6ff8bf9b55f..5981d6e25776 100644
--- a/net/l2tp/l2tp_ip6.c
+++ b/net/l2tp/l2tp_ip6.c
@@ -504,7 +504,7 @@ 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;
+	size_t ulen = len + transhdrlen;
 	int err;
 
 	/* Rough check on arithmetic overflow,
-- 
2.25.1

Re: [PATCH net-next v3] ipv6: Fix signed integer overflow in __ip6_append_data

[Jakub Kicinski]

On Sat, 28 May 2022 10:23:12 +0800 Wang Yufen wrote:
> diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
> index 55afd7f39c04..91704bbc7715 100644
> --- a/net/ipv6/udp.c
> +++ b/net/ipv6/udp.c
> @@ -1308,7 +1308,7 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
>  	struct ipcm6_cookie ipc6;
>  	int addr_len = msg->msg_namelen;
>  	bool connected = false;
> -	int ulen = len;
> +	size_t ulen = len;
>  	int corkreq = READ_ONCE(up->corkflag) || msg->msg_flags&MSG_MORE;
>  	int err;
>  	int is_udplite = IS_UDPLITE(sk);

No need to change ulen neither, it will not overflow and will be
promoted to size_t when passed to ip6_append_data() / ip6_make_skb().

Re: [PATCH net-next v3] ipv6: Fix signed integer overflow in __ip6_append_data

[wangyufen]

在 2022/6/1 12:35, Jakub Kicinski 写道:
> On Sat, 28 May 2022 10:23:12 +0800 Wang Yufen wrote:
>> diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
>> index 55afd7f39c04..91704bbc7715 100644
>> --- a/net/ipv6/udp.c
>> +++ b/net/ipv6/udp.c
>> @@ -1308,7 +1308,7 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
>>   	struct ipcm6_cookie ipc6;
>>   	int addr_len = msg->msg_namelen;
>>   	bool connected = false;
>> -	int ulen = len;
>> +	size_t ulen = len;
>>   	int corkreq = READ_ONCE(up->corkflag) || msg->msg_flags&MSG_MORE;
>>   	int err;
>>   	int is_udplite = IS_UDPLITE(sk);
> No need to change ulen neither, it will not overflow and will be
> promoted to size_t when passed to ip6_append_data() / ip6_make_skb().
> .
OK, thanks.