Messages in this thread | | | Date | Thu, 23 Jun 2022 20:20:25 +0800 (GMT+08:00) | From | duoming@zju ... | Subject | Re: [PATCH net 1/2] net: rose: fix UAF bugs caused by timer handler |
| |
Hello,
On Thu, 23 Jun 2022 11:13:41 +0200 Paolo Abeni wrote:
> > 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> > > --- > > net/rose/rose_timer.c | 22 +++++++++++++--------- > > 1 file changed, 13 insertions(+), 9 deletions(-) > > > > diff --git a/net/rose/rose_timer.c b/net/rose/rose_timer.c > > index b3138fc2e55..18d1912520b 100644 > > --- a/net/rose/rose_timer.c > > +++ b/net/rose/rose_timer.c > > @@ -36,7 +36,7 @@ void rose_start_heartbeat(struct sock *sk) > > 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) > > @@ -48,7 +48,7 @@ void rose_start_t1timer(struct sock *sk) > > 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) > > @@ -60,7 +60,7 @@ void rose_start_t2timer(struct sock *sk) > > 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) > > @@ -72,7 +72,7 @@ void rose_start_t3timer(struct sock *sk) > > 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) > > @@ -84,7 +84,7 @@ void rose_start_hbtimer(struct sock *sk) > > 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) > > @@ -97,23 +97,23 @@ void rose_start_idletimer(struct sock *sk) > > 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); > > A few lines above there is still a 'del_timer(&rose->idletimer);' call > which must be converted to sk_stop_timer(), otherwise there will be a > possible sk reference leak. > > There are other del_timer(&rose->timer) that need conversion.
Thank you for your time and suggestions! I will convert 'del_timer(&rose->idletimer);' and so on to sk_stop_timer().
Best regards, Duoming Zhou
| |