lkml.org 
[lkml]   [2018]   [Jan]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.9 43/66] sctp: do not allow the v4 socket to bind a v4mapped v6 address
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Xin Long <lucien.xin@gmail.com>


[ Upstream commit c5006b8aa74599ce19104b31d322d2ea9ff887cc ]

The check in sctp_sockaddr_af is not robust enough to forbid binding a
v4mapped v6 addr on a v4 socket.

The worse thing is that v4 socket's bind_verify would not convert this
v4mapped v6 addr to a v4 addr. syzbot even reported a crash as the v4
socket bound a v6 addr.

This patch is to fix it by doing the common sa.sa_family check first,
then AF_INET check for v4mapped v6 addrs.

Fixes: 7dab83de50c7 ("sctp: Support ipv6only AF_INET6 sockets.")
Reported-by: syzbot+7b7b518b1228d2743963@syzkaller.appspotmail.com
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/sctp/socket.c | 14 ++++++--------
1 file changed, 6 insertions(+), 8 deletions(-)

--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -332,16 +332,14 @@ static struct sctp_af *sctp_sockaddr_af(
if (len < sizeof (struct sockaddr))
return NULL;

+ if (!opt->pf->af_supported(addr->sa.sa_family, opt))
+ return NULL;
+
/* V4 mapped address are really of AF_INET family */
if (addr->sa.sa_family == AF_INET6 &&
- ipv6_addr_v4mapped(&addr->v6.sin6_addr)) {
- if (!opt->pf->af_supported(AF_INET, opt))
- return NULL;
- } else {
- /* Does this PF support this AF? */
- if (!opt->pf->af_supported(addr->sa.sa_family, opt))
- return NULL;
- }
+ ipv6_addr_v4mapped(&addr->v6.sin6_addr) &&
+ !opt->pf->af_supported(AF_INET, opt))
+ return NULL;

/* If we get this far, af is valid. */
af = sctp_get_af_specific(addr->sa.sa_family);

\
 
 \ /
  Last update: 2018-01-29 21:47    [W:0.466 / U:2.984 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site