* [PATCH net v3 0/2] Fix UAF and null-ptr-deref bugs in rose protocol @ 2022-06-24 1:05 Duoming Zhou 2022-06-24 1:05 ` [PATCH net v3 1/2] net: rose: fix UAF bugs caused by timer handler Duoming Zhou 2022-06-24 1:05 ` [PATCH net v3 2/2] net: rose: fix null-ptr-deref caused by rose_kill_by_neigh Duoming Zhou 0 siblings, 2 replies; 6+ messages in thread From: Duoming Zhou @ 2022-06-24 1:05 UTC (permalink / raw) To: linux-hams, pabeni Cc: ralf, davem, edumazet, kuba, netdev, linux-kernel, Duoming Zhou The first patch fixes the UAF bug of sock caused by timer. The second patch fixes the null-ptr-deref bug caused by rose_kill_by_neigh(). Duoming Zhou (2): net: rose: fix UAF bugs caused by timer handler net: rose: fix null-ptr-deref caused by rose_kill_by_neigh net/rose/af_rose.c | 6 ++++++ net/rose/rose_route.c | 2 ++ net/rose/rose_timer.c | 34 +++++++++++++++++++--------------- 3 files changed, 27 insertions(+), 15 deletions(-) -- 2.17.1 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH net v3 1/2] net: rose: fix UAF bugs caused by timer handler 2022-06-24 1:05 [PATCH net v3 0/2] Fix UAF and null-ptr-deref bugs in rose protocol Duoming Zhou @ 2022-06-24 1:05 ` Duoming Zhou 2022-06-24 1:05 ` [PATCH net v3 2/2] net: rose: fix null-ptr-deref caused by rose_kill_by_neigh Duoming Zhou 1 sibling, 0 replies; 6+ messages in thread From: Duoming Zhou @ 2022-06-24 1:05 UTC (permalink / raw) To: linux-hams, pabeni Cc: ralf, davem, edumazet, kuba, netdev, linux-kernel, Duoming Zhou 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> --- Changes in v3: - Change del_timer to sk_stop_timer in order to fix refcount leak. net/rose/rose_timer.c | 34 +++++++++++++++++++--------------- 1 file changed, 19 insertions(+), 15 deletions(-) diff --git a/net/rose/rose_timer.c b/net/rose/rose_timer.c index b3138fc2e55..f06ddbed3fe 100644 --- 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); } -- 2.17.1 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH net v3 2/2] net: rose: fix null-ptr-deref caused by rose_kill_by_neigh 2022-06-24 1:05 [PATCH net v3 0/2] Fix UAF and null-ptr-deref bugs in rose protocol Duoming Zhou 2022-06-24 1:05 ` [PATCH net v3 1/2] net: rose: fix UAF bugs caused by timer handler Duoming Zhou @ 2022-06-24 1:05 ` Duoming Zhou 2022-06-28 11:12 ` Paolo Abeni 1 sibling, 1 reply; 6+ messages in thread From: Duoming Zhou @ 2022-06-24 1:05 UTC (permalink / raw) To: linux-hams, pabeni Cc: ralf, davem, edumazet, kuba, netdev, linux-kernel, Duoming Zhou 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(). 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@zju.edu.cn> --- Changes since v2: - v2: Fix refcount leak of sock. net/rose/af_rose.c | 6 ++++++ net/rose/rose_route.c | 2 ++ 2 files changed, 8 insertions(+) diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c index bf2d986a6bc..5caa222c490 100644 --- a/net/rose/af_rose.c +++ b/net/rose/af_rose.c @@ -169,9 +169,15 @@ void rose_kill_by_neigh(struct rose_neigh *neigh) struct rose_sock *rose = rose_sk(s); if (rose->neighbour == neigh) { + sock_hold(s); rose_disconnect(s, ENETUNREACH, ROSE_OUT_OF_ORDER, 0); rose->neighbour->use--; + spin_unlock_bh(&rose_list_lock); + lock_sock(s); rose->neighbour = NULL; + release_sock(s); + spin_lock_bh(&rose_list_lock); + sock_put(s); } } spin_unlock_bh(&rose_list_lock); diff --git a/net/rose/rose_route.c b/net/rose/rose_route.c index fee6409c2bb..b116828b422 100644 --- a/net/rose/rose_route.c +++ b/net/rose/rose_route.c @@ -827,7 +827,9 @@ void rose_link_failed(ax25_cb *ax25, int reason) ax25_cb_put(ax25); rose_del_route_by_neigh(rose_neigh); + spin_unlock_bh(&rose_neigh_list_lock); rose_kill_by_neigh(rose_neigh); + return; } spin_unlock_bh(&rose_neigh_list_lock); } -- 2.17.1 ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH net v3 2/2] net: rose: fix null-ptr-deref caused by rose_kill_by_neigh 2022-06-24 1:05 ` [PATCH net v3 2/2] net: rose: fix null-ptr-deref caused by rose_kill_by_neigh Duoming Zhou @ 2022-06-28 11:12 ` Paolo Abeni 2022-06-29 3:48 ` duoming 0 siblings, 1 reply; 6+ messages in thread From: Paolo Abeni @ 2022-06-28 11:12 UTC (permalink / raw) To: Duoming Zhou, linux-hams Cc: ralf, davem, edumazet, kuba, netdev, linux-kernel On Fri, 2022-06-24 at 09:05 +0800, Duoming Zhou wrote: > 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(). > > 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@zju.edu.cn> > --- > Changes since v2: > - v2: Fix refcount leak of sock. > > net/rose/af_rose.c | 6 ++++++ > net/rose/rose_route.c | 2 ++ > 2 files changed, 8 insertions(+) > > diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c > index bf2d986a6bc..5caa222c490 100644 > --- a/net/rose/af_rose.c > +++ b/net/rose/af_rose.c > @@ -169,9 +169,15 @@ void rose_kill_by_neigh(struct rose_neigh *neigh) > struct rose_sock *rose = rose_sk(s); > > if (rose->neighbour == neigh) { > + sock_hold(s); > rose_disconnect(s, ENETUNREACH, ROSE_OUT_OF_ORDER, 0); > rose->neighbour->use--; > + spin_unlock_bh(&rose_list_lock); > + lock_sock(s); > rose->neighbour = NULL; > + release_sock(s); > + spin_lock_bh(&rose_list_lock); I'm sorry, I likely was not clear enough in my previous reply. This is broken. If a list is [spin_]lock protected, you can't release the lock, reacquire it and continue traversing the list from the [now invalid] same iterator. e.g. if s is removed from the list, even if the sock is not de- allocated due to the addtional refcount, the traversing will errnously stop after this sock, instead of continuing processing the remaining socks in the list. A possible alternative, not even build-tested would be: --- diff --git a/include/net/rose.h b/include/net/rose.h index 0f0a4ce0fee7..090db11d528f 100644 --- a/include/net/rose.h +++ b/include/net/rose.h @@ -145,6 +145,7 @@ struct rose_sock { struct rose_facilities_struct facilities; struct timer_list timer; struct timer_list idletimer; + struct rose_sock *dl_next; }; #define rose_sk(sk) ((struct rose_sock *)(sk)) diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c index 5caa222c490e..01f3c50f0921 100644 --- a/net/rose/af_rose.c +++ b/net/rose/af_rose.c @@ -162,25 +162,32 @@ static void rose_remove_socket(struct sock *sk) */ void rose_kill_by_neigh(struct rose_neigh *neigh) { - struct sock *s; + struct rose_sock *del_list = NULL; + struct sock *s, *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); if (rose->neighbour == neigh) { - sock_hold(s); - rose_disconnect(s, ENETUNREACH, ROSE_OUT_OF_ORDER, 0); - rose->neighbour->use--; - spin_unlock_bh(&rose_list_lock); - lock_sock(s); - rose->neighbour = NULL; - release_sock(s); - spin_lock_bh(&rose_list_lock); - sock_put(s); + __sk_del_node(s); + s->dl_next = del_list; + del_list = s; } } spin_unlock_bh(&rose_list_lock); + + while (del_list) { + s = del_list; + del_list = s->dl_next; + + lock_sock(s); + rose_disconnect(s, ENETUNREACH, ROSE_OUT_OF_ORDER, 0); + rose->neighbour->use--; + rose->neighbour = NULL; + release_sock(s); + sock_put(s); + } } /* --- Paolo ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH net v3 2/2] net: rose: fix null-ptr-deref caused by rose_kill_by_neigh 2022-06-28 11:12 ` Paolo Abeni @ 2022-06-29 3:48 ` duoming 2022-06-29 12:54 ` Dan Cross 0 siblings, 1 reply; 6+ messages in thread From: duoming @ 2022-06-29 3:48 UTC (permalink / raw) To: Paolo Abeni; +Cc: linux-hams, ralf, davem, edumazet, kuba, netdev, linux-kernel Hello, On Tue, 28 Jun 2022 13:12:40 +0200 Paolo Abeni wrote: > > 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(). > > > > 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@zju.edu.cn> > > --- > > Changes since v2: > > - v2: Fix refcount leak of sock. > > > > net/rose/af_rose.c | 6 ++++++ > > net/rose/rose_route.c | 2 ++ > > 2 files changed, 8 insertions(+) > > > > diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c > > index bf2d986a6bc..5caa222c490 100644 > > --- a/net/rose/af_rose.c > > +++ b/net/rose/af_rose.c > > @@ -169,9 +169,15 @@ void rose_kill_by_neigh(struct rose_neigh *neigh) > > struct rose_sock *rose = rose_sk(s); > > > > if (rose->neighbour == neigh) { > > + sock_hold(s); > > rose_disconnect(s, ENETUNREACH, ROSE_OUT_OF_ORDER, 0); > > rose->neighbour->use--; > > + spin_unlock_bh(&rose_list_lock); > > + lock_sock(s); > > rose->neighbour = NULL; > > + release_sock(s); > > + spin_lock_bh(&rose_list_lock); > > I'm sorry, I likely was not clear enough in my previous reply. This is > broken. If a list is [spin_]lock protected, you can't release the lock, > reacquire it and continue traversing the list from the [now invalid] > same iterator. > > e.g. if s is removed from the list, even if the sock is not de- > allocated due to the addtional refcount, the traversing will errnously > stop after this sock, instead of continuing processing the remaining > socks in the list. I understand. The following is a new solution: diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c index bf2d986a6bc..24dcbde88fb 100644 --- a/net/rose/af_rose.c +++ b/net/rose/af_rose.c @@ -165,13 +165,21 @@ void rose_kill_by_neigh(struct rose_neigh *neigh) struct sock *s; spin_lock_bh(&rose_list_lock); +again: sk_for_each(s, &rose_list) { struct rose_sock *rose = rose_sk(s); if (rose->neighbour == neigh) { + sock_hold(s); + spin_unlock_bh(&rose_list_lock); + lock_sock(s); rose_disconnect(s, ENETUNREACH, ROSE_OUT_OF_ORDER, 0); rose->neighbour->use--; rose->neighbour = NULL; + release_sock(s); + spin_lock_bh(&rose_list_lock); + sock_put(s); + goto again; } } spin_unlock_bh(&rose_list_lock); diff --git a/net/rose/rose_route.c b/net/rose/rose_route.c index fee6409c2bb..b116828b422 100644 --- a/net/rose/rose_route.c +++ b/net/rose/rose_route.c @@ -827,7 +827,9 @@ void rose_link_failed(ax25_cb *ax25, int reason) ax25_cb_put(ax25); rose_del_route_by_neigh(rose_neigh); + spin_unlock_bh(&rose_neigh_list_lock); rose_kill_by_neigh(rose_neigh); + return; } spin_unlock_bh(&rose_neigh_list_lock); } If s is removed from the list, the traversing will not stop erroneously. Best regards, Duoming Zhou ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH net v3 2/2] net: rose: fix null-ptr-deref caused by rose_kill_by_neigh 2022-06-29 3:48 ` duoming @ 2022-06-29 12:54 ` Dan Cross 0 siblings, 0 replies; 6+ messages in thread From: Dan Cross @ 2022-06-29 12:54 UTC (permalink / raw) To: duoming Cc: Paolo Abeni, linux-hams, ralf, davem, edumazet, kuba, netdev, linux-kernel On Tue, Jun 28, 2022 at 11:59 PM <duoming@zju.edu.cn> wrote: > Hello, > > On Tue, 28 Jun 2022 13:12:40 +0200 Paolo Abeni wrote: > > [snip] > > I'm sorry, I likely was not clear enough in my previous reply. This is > > broken. If a list is [spin_]lock protected, you can't release the lock, > > reacquire it and continue traversing the list from the [now invalid] > > same iterator. > > > > e.g. if s is removed from the list, even if the sock is not de- > > allocated due to the addtional refcount, the traversing will errnously > > stop after this sock, instead of continuing processing the remaining > > socks in the list. > > I understand. The following is a new solution: > > diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c > index bf2d986a6bc..24dcbde88fb 100644 > --- a/net/rose/af_rose.c > +++ b/net/rose/af_rose.c > @@ -165,13 +165,21 @@ void rose_kill_by_neigh(struct rose_neigh *neigh) > struct sock *s; > > spin_lock_bh(&rose_list_lock); > +again: > sk_for_each(s, &rose_list) { > struct rose_sock *rose = rose_sk(s); > > if (rose->neighbour == neigh) { > + sock_hold(s); > + spin_unlock_bh(&rose_list_lock); > + lock_sock(s); > rose_disconnect(s, ENETUNREACH, ROSE_OUT_OF_ORDER, 0); > rose->neighbour->use--; > rose->neighbour = NULL; > + release_sock(s); > + spin_lock_bh(&rose_list_lock); > + sock_put(s); > + goto again; It may be worthwhile noting that this changes the time complexity of the algorithm to be O(n^2) in the number of entries in `rose_list`, instead of linear. But as that number is extremely unlikely to ever be large, it probably makes no practical difference. - Dan C. > } > } > spin_unlock_bh(&rose_list_lock); > diff --git a/net/rose/rose_route.c b/net/rose/rose_route.c > index fee6409c2bb..b116828b422 100644 > --- a/net/rose/rose_route.c > +++ b/net/rose/rose_route.c > @@ -827,7 +827,9 @@ void rose_link_failed(ax25_cb *ax25, int reason) > ax25_cb_put(ax25); > > rose_del_route_by_neigh(rose_neigh); > + spin_unlock_bh(&rose_neigh_list_lock); > rose_kill_by_neigh(rose_neigh); > + return; > } > spin_unlock_bh(&rose_neigh_list_lock); > } > > If s is removed from the list, the traversing will not stop erroneously. > > Best regards, > Duoming Zhou ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-06-29 12:55 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2022-06-24 1:05 [PATCH net v3 0/2] Fix UAF and null-ptr-deref bugs in rose protocol Duoming Zhou 2022-06-24 1:05 ` [PATCH net v3 1/2] net: rose: fix UAF bugs caused by timer handler Duoming Zhou 2022-06-24 1:05 ` [PATCH net v3 2/2] net: rose: fix null-ptr-deref caused by rose_kill_by_neigh Duoming Zhou 2022-06-28 11:12 ` Paolo Abeni 2022-06-29 3:48 ` duoming 2022-06-29 12:54 ` Dan Cross
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