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stonezdmPaolo Abeni
stonezdm
authored and
Paolo Abeni
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net: rose: fix UAF bugs caused by timer handler
There are UAF bugs in rose_heartbeat_expiry(), rose_timer_expiry() and rose_idletimer_expiry(). The root cause is that del_timer() could not stop the timer handler that is running and the refcount of sock is not managed properly. One of the UAF bugs is shown below: (thread 1) | (thread 2) | rose_bind | rose_connect | rose_start_heartbeat rose_release | (wait a time) case ROSE_STATE_0 | rose_destroy_socket | rose_heartbeat_expiry rose_stop_heartbeat | sock_put(sk) | ... sock_put(sk) // FREE | | bh_lock_sock(sk) // USE The sock is deallocated by sock_put() in rose_release() and then used by bh_lock_sock() in rose_heartbeat_expiry(). Although rose_destroy_socket() calls rose_stop_heartbeat(), it could not stop the timer that is running. The KASAN report triggered by POC is shown below: BUG: KASAN: use-after-free in _raw_spin_lock+0x5a/0x110 Write of size 4 at addr ffff88800ae59098 by task swapper/3/0 ... Call Trace: <IRQ> dump_stack_lvl+0xbf/0xee print_address_description+0x7b/0x440 print_report+0x101/0x230 ? irq_work_single+0xbb/0x140 ? _raw_spin_lock+0x5a/0x110 kasan_report+0xed/0x120 ? _raw_spin_lock+0x5a/0x110 kasan_check_range+0x2bd/0x2e0 _raw_spin_lock+0x5a/0x110 rose_heartbeat_expiry+0x39/0x370 ? rose_start_heartbeat+0xb0/0xb0 call_timer_fn+0x2d/0x1c0 ? rose_start_heartbeat+0xb0/0xb0 expire_timers+0x1f3/0x320 __run_timers+0x3ff/0x4d0 run_timer_softirq+0x41/0x80 __do_softirq+0x233/0x544 irq_exit_rcu+0x41/0xa0 sysvec_apic_timer_interrupt+0x8c/0xb0 </IRQ> <TASK> asm_sysvec_apic_timer_interrupt+0x1b/0x20 RIP: 0010:default_idle+0xb/0x10 RSP: 0018:ffffc9000012fea0 EFLAGS: 00000202 RAX: 000000000000bcae RBX: ffff888006660f00 RCX: 000000000000bcae RDX: 0000000000000001 RSI: ffffffff843a11c0 RDI: ffffffff843a1180 RBP: dffffc0000000000 R08: dffffc0000000000 R09: ffffed100da36d46 R10: dfffe9100da36d47 R11: ffffffff83cf0950 R12: 0000000000000000 R13: 1ffff11000ccc1e0 R14: ffffffff8542af28 R15: dffffc0000000000 ... Allocated by task 146: __kasan_kmalloc+0xc4/0xf0 sk_prot_alloc+0xdd/0x1a0 sk_alloc+0x2d/0x4e0 rose_create+0x7b/0x330 __sock_create+0x2dd/0x640 __sys_socket+0xc7/0x270 __x64_sys_socket+0x71/0x80 do_syscall_64+0x43/0x90 entry_SYSCALL_64_after_hwframe+0x46/0xb0 Freed by task 152: kasan_set_track+0x4c/0x70 kasan_set_free_info+0x1f/0x40 ____kasan_slab_free+0x124/0x190 kfree+0xd3/0x270 __sk_destruct+0x314/0x460 rose_release+0x2fa/0x3b0 sock_close+0xcb/0x230 __fput+0x2d9/0x650 task_work_run+0xd6/0x160 exit_to_user_mode_loop+0xc7/0xd0 exit_to_user_mode_prepare+0x4e/0x80 syscall_exit_to_user_mode+0x20/0x40 do_syscall_64+0x4f/0x90 entry_SYSCALL_64_after_hwframe+0x46/0xb0 This patch adds refcount of sock when we use functions such as rose_start_heartbeat() and so on to start timer, and decreases the refcount of sock when timer is finished or deleted by functions such as rose_stop_heartbeat() and so on. As a result, the UAF bugs could be mitigated. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> Tested-by: Duoming Zhou <duoming@zju.edu.cn> Link: https://lore.kernel.org/r/20220629002640.5693-1-duoming@zju.edu.cn Signed-off-by: Paolo Abeni <pabeni@redhat.com>
1 parent f8ebb3a commit 9cc02ed

1 file changed

Lines changed: 19 additions & 15 deletions

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‎net/rose/rose_timer.c‎

Lines changed: 19 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -31,89 +31,89 @@ static void rose_idletimer_expiry(struct timer_list *);
3131

3232
void rose_start_heartbeat(struct sock *sk)
3333
{
34-
del_timer(&sk->sk_timer);
34+
sk_stop_timer(sk, &sk->sk_timer);
3535

3636
sk->sk_timer.function = rose_heartbeat_expiry;
3737
sk->sk_timer.expires = jiffies + 5 * HZ;
3838

39-
add_timer(&sk->sk_timer);
39+
sk_reset_timer(sk, &sk->sk_timer, sk->sk_timer.expires);
4040
}
4141

4242
void rose_start_t1timer(struct sock *sk)
4343
{
4444
struct rose_sock *rose = rose_sk(sk);
4545

46-
del_timer(&rose->timer);
46+
sk_stop_timer(sk, &rose->timer);
4747

4848
rose->timer.function = rose_timer_expiry;
4949
rose->timer.expires = jiffies + rose->t1;
5050

51-
add_timer(&rose->timer);
51+
sk_reset_timer(sk, &rose->timer, rose->timer.expires);
5252
}
5353

5454
void rose_start_t2timer(struct sock *sk)
5555
{
5656
struct rose_sock *rose = rose_sk(sk);
5757

58-
del_timer(&rose->timer);
58+
sk_stop_timer(sk, &rose->timer);
5959

6060
rose->timer.function = rose_timer_expiry;
6161
rose->timer.expires = jiffies + rose->t2;
6262

63-
add_timer(&rose->timer);
63+
sk_reset_timer(sk, &rose->timer, rose->timer.expires);
6464
}
6565

6666
void rose_start_t3timer(struct sock *sk)
6767
{
6868
struct rose_sock *rose = rose_sk(sk);
6969

70-
del_timer(&rose->timer);
70+
sk_stop_timer(sk, &rose->timer);
7171

7272
rose->timer.function = rose_timer_expiry;
7373
rose->timer.expires = jiffies + rose->t3;
7474

75-
add_timer(&rose->timer);
75+
sk_reset_timer(sk, &rose->timer, rose->timer.expires);
7676
}
7777

7878
void rose_start_hbtimer(struct sock *sk)
7979
{
8080
struct rose_sock *rose = rose_sk(sk);
8181

82-
del_timer(&rose->timer);
82+
sk_stop_timer(sk, &rose->timer);
8383

8484
rose->timer.function = rose_timer_expiry;
8585
rose->timer.expires = jiffies + rose->hb;
8686

87-
add_timer(&rose->timer);
87+
sk_reset_timer(sk, &rose->timer, rose->timer.expires);
8888
}
8989

9090
void rose_start_idletimer(struct sock *sk)
9191
{
9292
struct rose_sock *rose = rose_sk(sk);
9393

94-
del_timer(&rose->idletimer);
94+
sk_stop_timer(sk, &rose->idletimer);
9595

9696
if (rose->idle > 0) {
9797
rose->idletimer.function = rose_idletimer_expiry;
9898
rose->idletimer.expires = jiffies + rose->idle;
9999

100-
add_timer(&rose->idletimer);
100+
sk_reset_timer(sk, &rose->idletimer, rose->idletimer.expires);
101101
}
102102
}
103103

104104
void rose_stop_heartbeat(struct sock *sk)
105105
{
106-
del_timer(&sk->sk_timer);
106+
sk_stop_timer(sk, &sk->sk_timer);
107107
}
108108

109109
void rose_stop_timer(struct sock *sk)
110110
{
111-
del_timer(&rose_sk(sk)->timer);
111+
sk_stop_timer(sk, &rose_sk(sk)->timer);
112112
}
113113

114114
void rose_stop_idletimer(struct sock *sk)
115115
{
116-
del_timer(&rose_sk(sk)->idletimer);
116+
sk_stop_timer(sk, &rose_sk(sk)->idletimer);
117117
}
118118

119119
static void rose_heartbeat_expiry(struct timer_list *t)
@@ -130,6 +130,7 @@ static void rose_heartbeat_expiry(struct timer_list *t)
130130
(sk->sk_state == TCP_LISTEN && sock_flag(sk, SOCK_DEAD))) {
131131
bh_unlock_sock(sk);
132132
rose_destroy_socket(sk);
133+
sock_put(sk);
133134
return;
134135
}
135136
break;
@@ -152,6 +153,7 @@ static void rose_heartbeat_expiry(struct timer_list *t)
152153

153154
rose_start_heartbeat(sk);
154155
bh_unlock_sock(sk);
156+
sock_put(sk);
155157
}
156158

157159
static void rose_timer_expiry(struct timer_list *t)
@@ -181,6 +183,7 @@ static void rose_timer_expiry(struct timer_list *t)
181183
break;
182184
}
183185
bh_unlock_sock(sk);
186+
sock_put(sk);
184187
}
185188

186189
static void rose_idletimer_expiry(struct timer_list *t)
@@ -205,4 +208,5 @@ static void rose_idletimer_expiry(struct timer_list *t)
205208
sock_set_flag(sk, SOCK_DEAD);
206209
}
207210
bh_unlock_sock(sk);
211+
sock_put(sk);
208212
}

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