From: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
This patch has been added to the 3.12 stable tree. If you have any
objections, please let us know.
===============
[ Upstream commit 9a368aff9cb370298fa02feeffa861f2db497c18 ]
Several times already this has been reported as kasan reports caused by
syzkaller and trinity and people always looked at RCU races, but it is
much more simple. :)
In case we bind a pptp socket multiple times, we simply add it to
the callid_sock list but don't remove the old binding. Thus the old
socket stays in the bucket with unused call_id indexes and doesn't get
cleaned up. This causes various forms of kasan reports which were hard
to pinpoint.
Simply don't allow multiple binds and correct error handling in
pptp_bind. Also keep sk_state bits in place in pptp_connect.
Fixes: 00959ade36acad ("PPTP: PPP over IPv4 (Point-to-Point Tunneling Protocol)")
Cc: Dmitry Kozlov <xeb@xxxxxxx>
Cc: Sasha Levin <sasha.levin@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Dave Jones <davej@xxxxxxxxxxxxxxxxx>
Reported-by: Dave Jones <davej@xxxxxxxxxxxxxxxxx>
Signed-off-by: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
drivers/net/ppp/pptp.c | 34 ++++++++++++++++++++++++----------
1 file changed, 24 insertions(+), 10 deletions(-)
diff --git a/drivers/net/ppp/pptp.c b/drivers/net/ppp/pptp.c
index 0710214df2bf..bb1ab1ffbc8b 100644
--- a/drivers/net/ppp/pptp.c
+++ b/drivers/net/ppp/pptp.c
@@ -131,24 +131,27 @@ static int lookup_chan_dst(u16 call_id, __be32 d_addr)
return i < MAX_CALLID;
}
-static int add_chan(struct pppox_sock *sock)
+static int add_chan(struct pppox_sock *sock,
+ struct pptp_addr *sa)
{
static int call_id;
spin_lock(&chan_lock);
- if (!sock->proto.pptp.src_addr.call_id) {
+ if (!sa->call_id) {
call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, call_id + 1);
if (call_id == MAX_CALLID) {
call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, 1);
if (call_id == MAX_CALLID)
goto out_err;
}
- sock->proto.pptp.src_addr.call_id = call_id;
- } else if (test_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap))
+ sa->call_id = call_id;
+ } else if (test_bit(sa->call_id, callid_bitmap)) {
goto out_err;
+ }
- set_bit(sock->proto.pptp.src_addr.call_id, callid_bitmap);
- rcu_assign_pointer(callid_sock[sock->proto.pptp.src_addr.call_id], sock);
+ sock->proto.pptp.src_addr = *sa;
+ set_bit(sa->call_id, callid_bitmap);
+ rcu_assign_pointer(callid_sock[sa->call_id], sock);
spin_unlock(&chan_lock);
return 0;
@@ -417,7 +420,6 @@ static int pptp_bind(struct socket *sock, struct sockaddr *uservaddr,
struct sock *sk = sock->sk;
struct sockaddr_pppox *sp = (struct sockaddr_pppox *) uservaddr;
struct pppox_sock *po = pppox_sk(sk);
- struct pptp_opt *opt = &po->proto.pptp;
int error = 0;
if (sockaddr_len < sizeof(struct sockaddr_pppox))
@@ -425,10 +427,22 @@ static int pptp_bind(struct socket *sock, struct sockaddr *uservaddr,
lock_sock(sk);
- opt->src_addr = sp->sa_addr.pptp;
- if (add_chan(po))
+ if (sk->sk_state & PPPOX_DEAD) {
+ error = -EALREADY;
+ goto out;
+ }
+
+ if (sk->sk_state & PPPOX_BOUND) {
error = -EBUSY;
+ goto out;
+ }
+
+ if (add_chan(po, &sp->sa_addr.pptp))
+ error = -EBUSY;
+ else
+ sk->sk_state |= PPPOX_BOUND;
+out:
release_sock(sk);
return error;
}
@@ -499,7 +513,7 @@ static int pptp_connect(struct socket *sock, struct sockaddr *uservaddr,
}
opt->dst_addr = sp->sa_addr.pptp;
- sk->sk_state = PPPOX_CONNECTED;
+ sk->sk_state |= PPPOX_CONNECTED;
end:
release_sock(sk);
--
2.7.2
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