net: rose: fix UAF bugs caused by timer handler

stonezdm · Paolo Abeni · commit 9cc02ede6962 · 2022-06-30T11:07:30.000+02:00
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: 1da177e ("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>
diff --git a/net/rose/rose_timer.c b/net/rose/rose_timer.c
@@ -31,89 +31,89 @@ static void rose_idletimer_expiry(struct timer_list *);
 
 void rose_start_heartbeat(struct sock *sk)
 {
-	del_timer(&sk->sk_timer);
+	sk_stop_timer(sk, &sk->sk_timer);
 
 	sk->sk_timer.function = rose_heartbeat_expiry;
 	sk->sk_timer.expires  = jiffies + 5 * HZ;
 
-	add_timer(&sk->sk_timer);
+	sk_reset_timer(sk, &sk->sk_timer, sk->sk_timer.expires);
 }
 
 void rose_start_t1timer(struct sock *sk)
 {
 	struct rose_sock *rose = rose_sk(sk);
 
-	del_timer(&rose->timer);
+	sk_stop_timer(sk, &rose->timer);
 
 	rose->timer.function = rose_timer_expiry;
 	rose->timer.expires  = jiffies + rose->t1;
 
-	add_timer(&rose->timer);
+	sk_reset_timer(sk, &rose->timer, rose->timer.expires);
 }
 
 void rose_start_t2timer(struct sock *sk)
 {
 	struct rose_sock *rose = rose_sk(sk);
 
-	del_timer(&rose->timer);
+	sk_stop_timer(sk, &rose->timer);
 
 	rose->timer.function = rose_timer_expiry;
 	rose->timer.expires  = jiffies + rose->t2;
 
-	add_timer(&rose->timer);
+	sk_reset_timer(sk, &rose->timer, rose->timer.expires);
 }
 
 void rose_start_t3timer(struct sock *sk)
 {
 	struct rose_sock *rose = rose_sk(sk);
 
-	del_timer(&rose->timer);
+	sk_stop_timer(sk, &rose->timer);
 
 	rose->timer.function = rose_timer_expiry;
 	rose->timer.expires  = jiffies + rose->t3;
 
-	add_timer(&rose->timer);
+	sk_reset_timer(sk, &rose->timer, rose->timer.expires);
 }
 
 void rose_start_hbtimer(struct sock *sk)
 {
 	struct rose_sock *rose = rose_sk(sk);
 
-	del_timer(&rose->timer);
+	sk_stop_timer(sk, &rose->timer);
 
 	rose->timer.function = rose_timer_expiry;
 	rose->timer.expires  = jiffies + rose->hb;
 
-	add_timer(&rose->timer);
+	sk_reset_timer(sk, &rose->timer, rose->timer.expires);
 }
 
 void rose_start_idletimer(struct sock *sk)
 {
 	struct rose_sock *rose = rose_sk(sk);
 
-	del_timer(&rose->idletimer);
+	sk_stop_timer(sk, &rose->idletimer);
 
 	if (rose->idle > 0) {
 		rose->idletimer.function = rose_idletimer_expiry;
 		rose->idletimer.expires  = jiffies + rose->idle;
 
-		add_timer(&rose->idletimer);
+		sk_reset_timer(sk, &rose->idletimer, rose->idletimer.expires);
 	}
 }
 
 void rose_stop_heartbeat(struct sock *sk)
 {
-	del_timer(&sk->sk_timer);
+	sk_stop_timer(sk, &sk->sk_timer);
 }
 
 void rose_stop_timer(struct sock *sk)
 {
-	del_timer(&rose_sk(sk)->timer);
+	sk_stop_timer(sk, &rose_sk(sk)->timer);
 }
 
 void rose_stop_idletimer(struct sock *sk)
 {
-	del_timer(&rose_sk(sk)->idletimer);
+	sk_stop_timer(sk, &rose_sk(sk)->idletimer);
 }
 
 static void rose_heartbeat_expiry(struct timer_list *t)
@@ -130,6 +130,7 @@ static void rose_heartbeat_expiry(struct timer_list *t)
 		    (sk->sk_state == TCP_LISTEN && sock_flag(sk, SOCK_DEAD))) {
 			bh_unlock_sock(sk);
 			rose_destroy_socket(sk);
+			sock_put(sk);
 			return;
 		}
 		break;
@@ -152,6 +153,7 @@ static void rose_heartbeat_expiry(struct timer_list *t)
 
 	rose_start_heartbeat(sk);
 	bh_unlock_sock(sk);
+	sock_put(sk);
 }
 
 static void rose_timer_expiry(struct timer_list *t)
@@ -181,6 +183,7 @@ static void rose_timer_expiry(struct timer_list *t)
 		break;
 	}
 	bh_unlock_sock(sk);
+	sock_put(sk);
 }
 
 static void rose_idletimer_expiry(struct timer_list *t)
@@ -205,4 +208,5 @@ static void rose_idletimer_expiry(struct timer_list *t)
 		sock_set_flag(sk, SOCK_DEAD);
 	}
 	bh_unlock_sock(sk);
+	sock_put(sk);
 }

Original file line number	Diff line number	Diff line change
`@@ -31,89 +31,89 @@ static void rose_idletimer_expiry(struct timer_list *);`
`31`	`31`
`32`	`32`	`void rose_start_heartbeat(struct sock *sk)`
`33`	`33`	`{`
`34`		`- del_timer(&sk->sk_timer);`
	`34`	`+ sk_stop_timer(sk, &sk->sk_timer);`
`35`	`35`
`36`	`36`	`sk->sk_timer.function = rose_heartbeat_expiry;`
`37`	`37`	`sk->sk_timer.expires = jiffies + 5 * HZ;`
`38`	`38`
`39`		`- add_timer(&sk->sk_timer);`
	`39`	`+ sk_reset_timer(sk, &sk->sk_timer, sk->sk_timer.expires);`
`40`	`40`	`}`
`41`	`41`
`42`	`42`	`void rose_start_t1timer(struct sock *sk)`
`43`	`43`	`{`
`44`	`44`	`struct rose_sock *rose = rose_sk(sk);`
`45`	`45`
`46`		`- del_timer(&rose->timer);`
	`46`	`+ sk_stop_timer(sk, &rose->timer);`
`47`	`47`
`48`	`48`	`rose->timer.function = rose_timer_expiry;`
`49`	`49`	`rose->timer.expires = jiffies + rose->t1;`
`50`	`50`
`51`		`- add_timer(&rose->timer);`
	`51`	`+ sk_reset_timer(sk, &rose->timer, rose->timer.expires);`
`52`	`52`	`}`
`53`	`53`
`54`	`54`	`void rose_start_t2timer(struct sock *sk)`
`55`	`55`	`{`
`56`	`56`	`struct rose_sock *rose = rose_sk(sk);`
`57`	`57`
`58`		`- del_timer(&rose->timer);`
	`58`	`+ sk_stop_timer(sk, &rose->timer);`
`59`	`59`
`60`	`60`	`rose->timer.function = rose_timer_expiry;`
`61`	`61`	`rose->timer.expires = jiffies + rose->t2;`
`62`	`62`
`63`		`- add_timer(&rose->timer);`
	`63`	`+ sk_reset_timer(sk, &rose->timer, rose->timer.expires);`
`64`	`64`	`}`
`65`	`65`
`66`	`66`	`void rose_start_t3timer(struct sock *sk)`
`67`	`67`	`{`
`68`	`68`	`struct rose_sock *rose = rose_sk(sk);`
`69`	`69`
`70`		`- del_timer(&rose->timer);`
	`70`	`+ sk_stop_timer(sk, &rose->timer);`
`71`	`71`
`72`	`72`	`rose->timer.function = rose_timer_expiry;`
`73`	`73`	`rose->timer.expires = jiffies + rose->t3;`
`74`	`74`
`75`		`- add_timer(&rose->timer);`
	`75`	`+ sk_reset_timer(sk, &rose->timer, rose->timer.expires);`
`76`	`76`	`}`
`77`	`77`
`78`	`78`	`void rose_start_hbtimer(struct sock *sk)`
`79`	`79`	`{`
`80`	`80`	`struct rose_sock *rose = rose_sk(sk);`
`81`	`81`
`82`		`- del_timer(&rose->timer);`
	`82`	`+ sk_stop_timer(sk, &rose->timer);`
`83`	`83`
`84`	`84`	`rose->timer.function = rose_timer_expiry;`
`85`	`85`	`rose->timer.expires = jiffies + rose->hb;`
`86`	`86`
`87`		`- add_timer(&rose->timer);`
	`87`	`+ sk_reset_timer(sk, &rose->timer, rose->timer.expires);`
`88`	`88`	`}`
`89`	`89`
`90`	`90`	`void rose_start_idletimer(struct sock *sk)`
`91`	`91`	`{`
`92`	`92`	`struct rose_sock *rose = rose_sk(sk);`
`93`	`93`
`94`		`- del_timer(&rose->idletimer);`
	`94`	`+ sk_stop_timer(sk, &rose->idletimer);`
`95`	`95`
`96`	`96`	`if (rose->idle > 0) {`
`97`	`97`	`rose->idletimer.function = rose_idletimer_expiry;`
`98`	`98`	`rose->idletimer.expires = jiffies + rose->idle;`
`99`	`99`
`100`		`- add_timer(&rose->idletimer);`
	`100`	`+ sk_reset_timer(sk, &rose->idletimer, rose->idletimer.expires);`
`101`	`101`	`}`
`102`	`102`	`}`
`103`	`103`
`104`	`104`	`void rose_stop_heartbeat(struct sock *sk)`
`105`	`105`	`{`
`106`		`- del_timer(&sk->sk_timer);`
	`106`	`+ sk_stop_timer(sk, &sk->sk_timer);`
`107`	`107`	`}`
`108`	`108`
`109`	`109`	`void rose_stop_timer(struct sock *sk)`
`110`	`110`	`{`
`111`		`- del_timer(&rose_sk(sk)->timer);`
	`111`	`+ sk_stop_timer(sk, &rose_sk(sk)->timer);`
`112`	`112`	`}`
`113`	`113`
`114`	`114`	`void rose_stop_idletimer(struct sock *sk)`
`115`	`115`	`{`
`116`		`- del_timer(&rose_sk(sk)->idletimer);`
	`116`	`+ sk_stop_timer(sk, &rose_sk(sk)->idletimer);`
`117`	`117`	`}`
`118`	`118`
`119`	`119`	`static void rose_heartbeat_expiry(struct timer_list *t)`
`@@ -130,6 +130,7 @@ static void rose_heartbeat_expiry(struct timer_list *t)`
`130`	`130`	`(sk->sk_state == TCP_LISTEN && sock_flag(sk, SOCK_DEAD))) {`
`131`	`131`	`bh_unlock_sock(sk);`
`132`	`132`	`rose_destroy_socket(sk);`
	`133`	`+ sock_put(sk);`
`133`	`134`	`return;`
`134`	`135`	`}`
`135`	`136`	`break;`
`@@ -152,6 +153,7 @@ static void rose_heartbeat_expiry(struct timer_list *t)`
`152`	`153`
`153`	`154`	`rose_start_heartbeat(sk);`
`154`	`155`	`bh_unlock_sock(sk);`
	`156`	`+ sock_put(sk);`
`155`	`157`	`}`
`156`	`158`
`157`	`159`	`static void rose_timer_expiry(struct timer_list *t)`
`@@ -181,6 +183,7 @@ static void rose_timer_expiry(struct timer_list *t)`
`181`	`183`	`break;`
`182`	`184`	`}`
`183`	`185`	`bh_unlock_sock(sk);`
	`186`	`+ sock_put(sk);`
`184`	`187`	`}`
`185`	`188`
`186`	`189`	`static void rose_idletimer_expiry(struct timer_list *t)`
`@@ -205,4 +208,5 @@ static void rose_idletimer_expiry(struct timer_list *t)`
`205`	`208`	`sock_set_flag(sk, SOCK_DEAD);`
`206`	`209`	`}`
`207`	`210`	`bh_unlock_sock(sk);`
	`211`	`+ sock_put(sk);`
`208`	`212`	`}`