[PATCH net v6] net: rose: fix null-ptr-deref caused by rose_kill_by_neigh
From: Duoming Zhou
Date: Sun Jul 10 2022 - 21:31:38 EST
When the link layer connection is broken, the rose->neighbour is
set to null. But rose->neighbour could be used by rose_connection()
and rose_release() later, because there is no synchronization among
them. As a result, the null-ptr-deref bugs will happen.
One of the null-ptr-deref bugs is shown below:
(thread 1) | (thread 2)
| rose_connect
rose_kill_by_neigh | lock_sock(sk)
spin_lock_bh(&rose_list_lock) | if (!rose->neighbour)
rose->neighbour = NULL;//(1) |
| rose->neighbour->use++;//(2)
The rose->neighbour is set to null in position (1) and dereferenced
in position (2).
The KASAN report triggered by POC is shown below:
KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
...
RIP: 0010:rose_connect+0x6c2/0xf30
RSP: 0018:ffff88800ab47d60 EFLAGS: 00000206
RAX: 0000000000000005 RBX: 000000000000002a RCX: 0000000000000000
RDX: ffff88800ab38000 RSI: ffff88800ab47e48 RDI: ffff88800ab38309
RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffed1001567062
R10: dfffe91001567063 R11: 1ffff11001567061 R12: 1ffff11000d17cd0
R13: ffff8880068be680 R14: 0000000000000002 R15: 1ffff11000d17cd0
...
Call Trace:
<TASK>
? __local_bh_enable_ip+0x54/0x80
? selinux_netlbl_socket_connect+0x26/0x30
? rose_bind+0x5b0/0x5b0
__sys_connect+0x216/0x280
__x64_sys_connect+0x71/0x80
do_syscall_64+0x43/0x90
entry_SYSCALL_64_after_hwframe+0x46/0xb0
This patch adds lock_sock() in rose_kill_by_neigh() in order to
synchronize with rose_connect() and rose_release(). Then, changing
type of 'neighbour->use' from unsigned short to atomic_t in order to
mitigate race conditions caused by holding different socket lock while
updating 'neighbour->use'.
Meanwhile, this patch adds sock_hold() protected by rose_list_lock
that could synchronize with rose_remove_socket() in order to mitigate
UAF bug caused by lock_sock() we add.
What's more, there is no need using rose_neigh_list_lock to protect
rose_kill_by_neigh(). Because we have already used rose_neigh_list_lock
to protect the state change of rose_neigh in rose_link_failed(), which
is well synchronized.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Duoming Zhou <duoming@xxxxxxxxxx>
---
Changes in v6:
- Change sk_for_each() to sk_for_each_safe().
- Change type of 'neighbour->use' from unsigned short to atomic_t.
include/net/rose.h | 2 +-
net/rose/af_rose.c | 19 +++++++++++++------
net/rose/rose_in.c | 12 ++++++------
net/rose/rose_route.c | 24 ++++++++++++------------
net/rose/rose_timer.c | 2 +-
5 files changed, 33 insertions(+), 26 deletions(-)
diff --git a/include/net/rose.h b/include/net/rose.h
index 0f0a4ce0fee..d5ddebc556d 100644
--- a/include/net/rose.h
+++ b/include/net/rose.h
@@ -95,7 +95,7 @@ struct rose_neigh {
ax25_cb *ax25;
struct net_device *dev;
unsigned short count;
- unsigned short use;
+ atomic_t use;
unsigned int number;
char restarted;
char dce_mode;
diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c
index bf2d986a6bc..54e7b76c4f3 100644
--- a/net/rose/af_rose.c
+++ b/net/rose/af_rose.c
@@ -163,16 +163,23 @@ static void rose_remove_socket(struct sock *sk)
void rose_kill_by_neigh(struct rose_neigh *neigh)
{
struct sock *s;
+ struct hlist_node *tmp;
spin_lock_bh(&rose_list_lock);
- sk_for_each(s, &rose_list) {
+ sk_for_each_safe(s, tmp, &rose_list) {
struct rose_sock *rose = rose_sk(s);
+ sock_hold(s);
+ spin_unlock_bh(&rose_list_lock);
+ lock_sock(s);
if (rose->neighbour == neigh) {
rose_disconnect(s, ENETUNREACH, ROSE_OUT_OF_ORDER, 0);
- rose->neighbour->use--;
+ atomic_dec(&rose->neighbour->use);
rose->neighbour = NULL;
}
+ release_sock(s);
+ sock_put(s);
+ spin_lock_bh(&rose_list_lock);
}
spin_unlock_bh(&rose_list_lock);
}
@@ -191,7 +198,7 @@ static void rose_kill_by_device(struct net_device *dev)
if (rose->device == dev) {
rose_disconnect(s, ENETUNREACH, ROSE_OUT_OF_ORDER, 0);
if (rose->neighbour)
- rose->neighbour->use--;
+ atomic_dec(&rose->neighbour->use);
rose->device = NULL;
}
}
@@ -618,7 +625,7 @@ static int rose_release(struct socket *sock)
break;
case ROSE_STATE_2:
- rose->neighbour->use--;
+ atomic_dec(&rose->neighbour->use);
release_sock(sk);
rose_disconnect(sk, 0, -1, -1);
lock_sock(sk);
@@ -819,7 +826,7 @@ static int rose_connect(struct socket *sock, struct sockaddr *uaddr, int addr_le
rose->state = ROSE_STATE_1;
- rose->neighbour->use++;
+ atomic_inc(&rose->neighbour->use);
rose_write_internal(sk, ROSE_CALL_REQUEST);
rose_start_heartbeat(sk);
@@ -1019,7 +1026,7 @@ int rose_rx_call_request(struct sk_buff *skb, struct net_device *dev, struct ros
make_rose->device = dev;
make_rose->facilities = facilities;
- make_rose->neighbour->use++;
+ atomic_inc(&make_rose->neighbour->use);
if (rose_sk(sk)->defer) {
make_rose->state = ROSE_STATE_5;
diff --git a/net/rose/rose_in.c b/net/rose/rose_in.c
index 4d67f36dce1..86168f29943 100644
--- a/net/rose/rose_in.c
+++ b/net/rose/rose_in.c
@@ -56,7 +56,7 @@ static int rose_state1_machine(struct sock *sk, struct sk_buff *skb, int framety
case ROSE_CLEAR_REQUEST:
rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
rose_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
- rose->neighbour->use--;
+ atomic_dec(&rose->neighbour->use);
break;
default:
@@ -79,12 +79,12 @@ static int rose_state2_machine(struct sock *sk, struct sk_buff *skb, int framety
case ROSE_CLEAR_REQUEST:
rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
- rose->neighbour->use--;
+ atomic_dec(&rose->neighbour->use);
break;
case ROSE_CLEAR_CONFIRMATION:
rose_disconnect(sk, 0, -1, -1);
- rose->neighbour->use--;
+ atomic_dec(&rose->neighbour->use);
break;
default:
@@ -120,7 +120,7 @@ static int rose_state3_machine(struct sock *sk, struct sk_buff *skb, int framety
case ROSE_CLEAR_REQUEST:
rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
- rose->neighbour->use--;
+ atomic_dec(&rose->neighbour->use);
break;
case ROSE_RR:
@@ -233,7 +233,7 @@ static int rose_state4_machine(struct sock *sk, struct sk_buff *skb, int framety
case ROSE_CLEAR_REQUEST:
rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
- rose->neighbour->use--;
+ atomic_dec(&rose->neighbour->use);
break;
default:
@@ -253,7 +253,7 @@ static int rose_state5_machine(struct sock *sk, struct sk_buff *skb, int framety
if (frametype == ROSE_CLEAR_REQUEST) {
rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
- rose_sk(sk)->neighbour->use--;
+ atomic_dec(&rose_sk(sk)->neighbour->use);
}
return 0;
diff --git a/net/rose/rose_route.c b/net/rose/rose_route.c
index eb0b8197ac8..8be00a44540 100644
--- a/net/rose/rose_route.c
+++ b/net/rose/rose_route.c
@@ -93,7 +93,7 @@ static int __must_check rose_add_node(struct rose_route_struct *rose_route,
rose_neigh->ax25 = NULL;
rose_neigh->dev = dev;
rose_neigh->count = 0;
- rose_neigh->use = 0;
+ atomic_set(&rose_neigh->use, 0);
rose_neigh->dce_mode = 0;
rose_neigh->loopback = 0;
rose_neigh->number = rose_neigh_no++;
@@ -263,10 +263,10 @@ static void rose_remove_route(struct rose_route *rose_route)
struct rose_route *s;
if (rose_route->neigh1 != NULL)
- rose_route->neigh1->use--;
+ atomic_dec(&rose_route->neigh1->use);
if (rose_route->neigh2 != NULL)
- rose_route->neigh2->use--;
+ atomic_dec(&rose_route->neigh2->use);
if ((s = rose_route_list) == rose_route) {
rose_route_list = rose_route->next;
@@ -331,7 +331,7 @@ static int rose_del_node(struct rose_route_struct *rose_route,
if (rose_node->neighbour[i] == rose_neigh) {
rose_neigh->count--;
- if (rose_neigh->count == 0 && rose_neigh->use == 0)
+ if (rose_neigh->count == 0 && atomic_read(&rose_neigh->use) == 0)
rose_remove_neigh(rose_neigh);
rose_node->count--;
@@ -381,7 +381,7 @@ void rose_add_loopback_neigh(void)
sn->ax25 = NULL;
sn->dev = NULL;
sn->count = 0;
- sn->use = 0;
+ atomic_set(&sn->use, 0);
sn->dce_mode = 1;
sn->loopback = 1;
sn->number = rose_neigh_no++;
@@ -573,7 +573,7 @@ static int rose_clear_routes(void)
s = rose_neigh;
rose_neigh = rose_neigh->next;
- if (s->use == 0 && !s->loopback) {
+ if (atomic_read(&s->use) == 0 && !s->loopback) {
s->count = 0;
rose_remove_neigh(s);
}
@@ -789,13 +789,13 @@ static void rose_del_route_by_neigh(struct rose_neigh *rose_neigh)
}
if (rose_route->neigh1 == rose_neigh) {
- rose_route->neigh1->use--;
+ atomic_dec(&rose_route->neigh1->use);
rose_route->neigh1 = NULL;
rose_transmit_clear_request(rose_route->neigh2, rose_route->lci2, ROSE_OUT_OF_ORDER, 0);
}
if (rose_route->neigh2 == rose_neigh) {
- rose_route->neigh2->use--;
+ atomic_dec(&rose_route->neigh2->use);
rose_route->neigh2 = NULL;
rose_transmit_clear_request(rose_route->neigh1, rose_route->lci1, ROSE_OUT_OF_ORDER, 0);
}
@@ -924,7 +924,7 @@ int rose_route_frame(struct sk_buff *skb, ax25_cb *ax25)
rose_clear_queues(sk);
rose->cause = ROSE_NETWORK_CONGESTION;
rose->diagnostic = 0;
- rose->neighbour->use--;
+ atomic_dec(&rose->neighbour->use);
rose->neighbour = NULL;
rose->lci = 0;
rose->state = ROSE_STATE_0;
@@ -1067,8 +1067,8 @@ int rose_route_frame(struct sk_buff *skb, ax25_cb *ax25)
rose_route->lci2 = new_lci;
rose_route->neigh2 = new_neigh;
- rose_route->neigh1->use++;
- rose_route->neigh2->use++;
+ atomic_inc(&rose_route->neigh1->use);
+ atomic_inc(&rose_route->neigh2->use);
rose_route->next = rose_route_list;
rose_route_list = rose_route;
@@ -1195,7 +1195,7 @@ static int rose_neigh_show(struct seq_file *seq, void *v)
(rose_neigh->loopback) ? "RSLOOP-0" : ax2asc(buf, &rose_neigh->callsign),
rose_neigh->dev ? rose_neigh->dev->name : "???",
rose_neigh->count,
- rose_neigh->use,
+ atomic_read(&rose_neigh->use),
(rose_neigh->dce_mode) ? "DCE" : "DTE",
(rose_neigh->restarted) ? "yes" : "no",
ax25_display_timer(&rose_neigh->t0timer) / HZ,
diff --git a/net/rose/rose_timer.c b/net/rose/rose_timer.c
index f06ddbed3fe..9dfd4eae5d5 100644
--- a/net/rose/rose_timer.c
+++ b/net/rose/rose_timer.c
@@ -171,7 +171,7 @@ static void rose_timer_expiry(struct timer_list *t)
break;
case ROSE_STATE_2: /* T3 */
- rose->neighbour->use--;
+ atomic_dec(&rose->neighbour->use);
rose_disconnect(sk, ETIMEDOUT, -1, -1);
break;
--
2.17.1