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authorXin Long <lucien.xin@gmail.com>2018-01-15 17:02:00 +0800
committerDavid S. Miller <davem@davemloft.net>2018-01-16 14:24:20 -0500
commitc5006b8aa74599ce19104b31d322d2ea9ff887cc (patch)
tree116feac3332f40168ff3ba971256564bcb9b2b3f
parenta0ff660058b88d12625a783ce9e5c1371c87951f (diff)
sctp: do not allow the v4 socket to bind a v4mapped v6 address
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>
-rw-r--r--net/sctp/socket.c14
1 files changed, 6 insertions, 8 deletions
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index feb2ca69827a..039fcb618c34 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -335,16 +335,14 @@ static struct sctp_af *sctp_sockaddr_af(struct sctp_sock *opt,
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);