[PATCH net v2] mptcp: bugfix for RM_ADDR option parsing

[PATCH net v2] mptcp: bugfix for RM_ADDR option parsing

[Geliang Tang]

In MPTCPOPT_RM_ADDR option parsing, the pointer "ptr" pointed to the
"Subtype" octet, the pointer "ptr+1" pointed to the "Address ID" octet:

  +-------+-------+---------------+
  |Subtype|(resvd)|   Address ID  |
  +-------+-------+---------------+
  |               |
 ptr            ptr+1

We should set mp_opt->rm_id to the value of "ptr+1", not "ptr". This patch
will fix this bug.

Fixes: 3df523ab582c ("mptcp: Add ADD_ADDR handling")
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
---
 Changes in v2:
  - Add "-net" subject and "Fixes" tag as Matt suggested.
---
 net/mptcp/options.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 01f1f4cf4902..490b92534afc 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -273,6 +273,8 @@ static void mptcp_parse_option(const struct sk_buff *skb,
 		if (opsize != TCPOLEN_MPTCP_RM_ADDR_BASE)
 			break;
 
+		ptr++;
+
 		mp_opt->rm_addr = 1;
 		mp_opt->rm_id = *ptr++;
 		pr_debug("RM_ADDR: id=%d", mp_opt->rm_id);
-- 
2.17.1

Re: [PATCH net v2] mptcp: bugfix for RM_ADDR option parsing

[Matthieu Baerts]

Hi Geliang,

On 08/06/2020 12:47, Geliang Tang wrote:
> In MPTCPOPT_RM_ADDR option parsing, the pointer "ptr" pointed to the
> "Subtype" octet, the pointer "ptr+1" pointed to the "Address ID" octet:
> 
>    +-------+-------+---------------+
>    |Subtype|(resvd)|   Address ID  |
>    +-------+-------+---------------+
>    |               |
>   ptr            ptr+1
> 
> We should set mp_opt->rm_id to the value of "ptr+1", not "ptr". This patch
> will fix this bug.
> 
> Fixes: 3df523ab582c ("mptcp: Add ADD_ADDR handling")
> Signed-off-by: Geliang Tang <geliangtang@gmail.com>
> ---
>   Changes in v2:
>    - Add "-net" subject and "Fixes" tag as Matt suggested.

Thanks for this v2! LGTM!

Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>

Cheers,
Matt
-- 
Matthieu Baerts | R&D Engineer
matthieu.baerts@tessares.net
Tessares SA | Hybrid Access Solutions
www.tessares.net
1 Avenue Jean Monnet, 1348 Louvain-la-Neuve, Belgium

Re: [PATCH net v2] mptcp: bugfix for RM_ADDR option parsing

[David Miller]

From: Geliang Tang <geliangtang@gmail.com>
Date: Mon,  8 Jun 2020 18:47:54 +0800

> In MPTCPOPT_RM_ADDR option parsing, the pointer "ptr" pointed to the
> "Subtype" octet, the pointer "ptr+1" pointed to the "Address ID" octet:
> 
>   +-------+-------+---------------+
>   |Subtype|(resvd)|   Address ID  |
>   +-------+-------+---------------+
>   |               |
>  ptr            ptr+1
> 
> We should set mp_opt->rm_id to the value of "ptr+1", not "ptr". This patch
> will fix this bug.
> 
> Fixes: 3df523ab582c ("mptcp: Add ADD_ADDR handling")
> Signed-off-by: Geliang Tang <geliangtang@gmail.com>
> ---
>  Changes in v2:
>   - Add "-net" subject and "Fixes" tag as Matt suggested.

Applied and queued up for v5.7 -stable, thanks!