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Message-ID: <CADvbK_cPqbBRvm3qGGdG_9jcShXG8Xyy6BXqzEKC-RMttHXNNw@mail.gmail.com>
Date: Thu, 20 Feb 2020 23:44:55 +0800
From: Xin Long <lucien.xin@...il.com>
To: Dmitry Vyukov <dvyukov@...gle.com>
Cc: Ying Xue <ying.xue@...driver.com>,
David Miller <davem@...emloft.net>,
netdev <netdev@...r.kernel.org>, Hillf Danton <hdanton@...a.com>,
tipc-discussion@...ts.sourceforge.net,
syzkaller-bugs <syzkaller-bugs@...glegroups.com>,
Jakub Kicinski <jakub.kicinski@...ronome.com>,
jmaloy@...hat.com
Subject: Re: [PATCH v2 3/3] tipc: fix issue of calling smp_processor_id() in preemptible
On Wed, Feb 19, 2020 at 4:34 PM Dmitry Vyukov <dvyukov@...gle.com> wrote:
>
> On Wed, Feb 19, 2020 at 9:29 AM Dmitry Vyukov <dvyukov@...gle.com> wrote:
> >
> > On Mon, Aug 12, 2019 at 9:44 AM Ying Xue <ying.xue@...driver.com> wrote:
> > >
> > > syzbot found the following issue:
> > >
> > > [ 81.119772][ T8612] BUG: using smp_processor_id() in preemptible [00000000] code: syz-executor834/8612
> > > [ 81.136212][ T8612] caller is dst_cache_get+0x3d/0xb0
> > > [ 81.141450][ T8612] CPU: 0 PID: 8612 Comm: syz-executor834 Not tainted 5.2.0-rc6+ #48
> > > [ 81.149435][ T8612] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > > [ 81.159480][ T8612] Call Trace:
> > > [ 81.162789][ T8612] dump_stack+0x172/0x1f0
> > > [ 81.167123][ T8612] debug_smp_processor_id+0x251/0x280
> > > [ 81.172479][ T8612] dst_cache_get+0x3d/0xb0
> > > [ 81.176928][ T8612] tipc_udp_xmit.isra.0+0xc4/0xb80
> > > [ 81.182046][ T8612] ? kasan_kmalloc+0x9/0x10
> > > [ 81.186531][ T8612] ? tipc_udp_addr2str+0x170/0x170
> > > [ 81.191641][ T8612] ? __copy_skb_header+0x2e8/0x560
> > > [ 81.196750][ T8612] ? __skb_checksum_complete+0x3f0/0x3f0
> > > [ 81.202364][ T8612] ? netdev_alloc_frag+0x1b0/0x1b0
> > > [ 81.207452][ T8612] ? skb_copy_header+0x21/0x2b0
> > > [ 81.212282][ T8612] ? __pskb_copy_fclone+0x516/0xc90
> > > [ 81.217470][ T8612] tipc_udp_send_msg+0x29a/0x4b0
In tipc_bearer_xmit_skb(), b->media->send_msg()/tipc_udp_send_msg()
is called under rcu_read_lock(), which is already ensure it's a
non-preemptible context.
What I saw here is imbalance rcu_read_(un)lock() call somewhere.
> > > [ 81.222400][ T8612] tipc_bearer_xmit_skb+0x16c/0x360
> > > [ 81.227585][ T8612] tipc_enable_bearer+0xabe/0xd20
> > > [ 81.232606][ T8612] ? __nla_validate_parse+0x2d0/0x1ee0
> > > [ 81.238048][ T8612] ? tipc_bearer_xmit_skb+0x360/0x360
> > > [ 81.243401][ T8612] ? nla_memcpy+0xb0/0xb0
> > > [ 81.247710][ T8612] ? nla_memcpy+0xb0/0xb0
> > > [ 81.252020][ T8612] ? __nla_parse+0x43/0x60
> > > [ 81.256417][ T8612] __tipc_nl_bearer_enable+0x2de/0x3a0
> > > [ 81.261856][ T8612] ? __tipc_nl_bearer_enable+0x2de/0x3a0
> > > [ 81.267467][ T8612] ? tipc_nl_bearer_disable+0x40/0x40
> > > [ 81.272848][ T8612] ? unwind_get_return_address+0x58/0xa0
> > > [ 81.278501][ T8612] ? lock_acquire+0x16f/0x3f0
> > > [ 81.283190][ T8612] tipc_nl_bearer_enable+0x23/0x40
> > > [ 81.288300][ T8612] genl_family_rcv_msg+0x74b/0xf90
> > > [ 81.293404][ T8612] ? genl_unregister_family+0x790/0x790
> > > [ 81.298935][ T8612] ? __lock_acquire+0x54f/0x5490
> > > [ 81.303852][ T8612] ? __netlink_lookup+0x3fa/0x7b0
> > > [ 81.308865][ T8612] genl_rcv_msg+0xca/0x16c
> > > [ 81.313266][ T8612] netlink_rcv_skb+0x177/0x450
> > > [ 81.318043][ T8612] ? genl_family_rcv_msg+0xf90/0xf90
> > > [ 81.323311][ T8612] ? netlink_ack+0xb50/0xb50
> > > [ 81.327906][ T8612] ? lock_acquire+0x16f/0x3f0
> > > [ 81.332589][ T8612] ? kasan_check_write+0x14/0x20
> > > [ 81.337511][ T8612] genl_rcv+0x29/0x40
> > > [ 81.341485][ T8612] netlink_unicast+0x531/0x710
> > > [ 81.346268][ T8612] ? netlink_attachskb+0x770/0x770
> > > [ 81.351374][ T8612] ? _copy_from_iter_full+0x25d/0x8c0
> > > [ 81.356765][ T8612] ? __sanitizer_cov_trace_cmp8+0x18/0x20
> > > [ 81.362479][ T8612] ? __check_object_size+0x3d/0x42f
> > > [ 81.367667][ T8612] netlink_sendmsg+0x8ae/0xd70
> > > [ 81.372415][ T8612] ? netlink_unicast+0x710/0x710
> > > [ 81.377520][ T8612] ? aa_sock_msg_perm.isra.0+0xba/0x170
> > > [ 81.383051][ T8612] ? apparmor_socket_sendmsg+0x2a/0x30
> > > [ 81.388530][ T8612] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20
> > > [ 81.394775][ T8612] ? security_socket_sendmsg+0x8d/0xc0
> > > [ 81.400240][ T8612] ? netlink_unicast+0x710/0x710
> > > [ 81.405161][ T8612] sock_sendmsg+0xd7/0x130
> > > [ 81.409561][ T8612] ___sys_sendmsg+0x803/0x920
> > > [ 81.414220][ T8612] ? copy_msghdr_from_user+0x430/0x430
> > > [ 81.419667][ T8612] ? _raw_spin_unlock_irqrestore+0x6b/0xe0
> > > [ 81.425461][ T8612] ? debug_object_active_state+0x25d/0x380
> > > [ 81.431255][ T8612] ? __lock_acquire+0x54f/0x5490
> > > [ 81.436174][ T8612] ? kasan_check_read+0x11/0x20
> > > [ 81.441208][ T8612] ? _raw_spin_unlock_irqrestore+0xa4/0xe0
> > > [ 81.447008][ T8612] ? mark_held_locks+0xf0/0xf0
> > > [ 81.451768][ T8612] ? __call_rcu.constprop.0+0x28b/0x720
> > > [ 81.457298][ T8612] ? call_rcu+0xb/0x10
> > > [ 81.461353][ T8612] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20
> > > [ 81.467589][ T8612] ? __fget_light+0x1a9/0x230
> > > [ 81.472249][ T8612] ? __fdget+0x1b/0x20
> > > [ 81.476301][ T8612] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20
> > > [ 81.482545][ T8612] __sys_sendmsg+0x105/0x1d0
> > > [ 81.487115][ T8612] ? __ia32_sys_shutdown+0x80/0x80
> > > [ 81.492208][ T8612] ? blkcg_maybe_throttle_current+0x5e2/0xfb0
> > > [ 81.498272][ T8612] ? trace_hardirqs_on_thunk+0x1a/0x1c
> > > [ 81.503726][ T8612] ? do_syscall_64+0x26/0x680
> > > [ 81.508385][ T8612] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe
> > > [ 81.514444][ T8612] ? do_syscall_64+0x26/0x680
> > > [ 81.519110][ T8612] __x64_sys_sendmsg+0x78/0xb0
> > > [ 81.523862][ T8612] do_syscall_64+0xfd/0x680
> > > [ 81.528352][ T8612] entry_SYSCALL_64_after_hwframe+0x49/0xbe
> > > [ 81.534234][ T8612] RIP: 0033:0x444679
> > > [ 81.538114][ T8612] Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 1b d8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> > > [ 81.557709][ T8612] RSP: 002b:00007fff0201a8b8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> > > [ 81.566147][ T8612] RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000444679
> > > [ 81.574108][ T8612] RDX: 0000000000000000 RSI: 0000000020000580 RDI: 0000000000000003
> > > [ 81.582152][ T8612] RBP: 00000000006cf018 R08: 0000000000000001 R09: 00000000004002e0
> > > [ 81.590113][ T8612] R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000402320
> > > [ 81.598089][ T8612] R13: 00000000004023b0 R14: 0000000000000000 R15: 0000000000
> > >
> > > In commit e9c1a793210f ("tipc: add dst_cache support for udp media")
> > > dst_cache_get() was introduced to be called in tipc_udp_xmit(). But
> > > smp_processor_id() called by dst_cache_get() cannot be invoked in
> > > preemptible context, as a result, the complaint above was reported.
> > >
> > > Fixes: e9c1a793210f ("tipc: add dst_cache support for udp media")
> > > Reported-by: syzbot+1a68504d96cd17b33a05@...kaller.appspotmail.com
> > > Signed-off-by: Hillf Danton <hdanton@...a.com>
> > > Signed-off-by: Ying Xue <ying.xue@...driver.com>
> >
> > Hi,
> >
> > Was this ever merged?
> > The bug is still open, alive and kicking:
> > https://syzkaller.appspot.com/bug?extid=1a68504d96cd17b33a05
> >
> > and one of the top crashers currently.
> > Along with few other top crashers, these bugs prevent most of the
> > other kernel testing from happening.
>
> /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
>
> +jmaloy new email address
>
> > > ---
> > > net/tipc/udp_media.c | 12 +++++++++---
> > > 1 file changed, 9 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/net/tipc/udp_media.c b/net/tipc/udp_media.c
> > > index 287df687..ca3ae2e 100644
> > > --- a/net/tipc/udp_media.c
> > > +++ b/net/tipc/udp_media.c
> > > @@ -224,6 +224,8 @@ static int tipc_udp_send_msg(struct net *net, struct sk_buff *skb,
> > > struct udp_bearer *ub;
> > > int err = 0;
> > >
> > > + local_bh_disable();
> > > +
> > > if (skb_headroom(skb) < UDP_MIN_HEADROOM) {
> > > err = pskb_expand_head(skb, UDP_MIN_HEADROOM, 0, GFP_ATOMIC);
> > > if (err)
> > > @@ -237,9 +239,12 @@ static int tipc_udp_send_msg(struct net *net, struct sk_buff *skb,
> > > goto out;
> > > }
> > >
> > > - if (addr->broadcast != TIPC_REPLICAST_SUPPORT)
> > > - return tipc_udp_xmit(net, skb, ub, src, dst,
> > > - &ub->rcast.dst_cache);
> > > + if (addr->broadcast != TIPC_REPLICAST_SUPPORT) {
> > > + err = tipc_udp_xmit(net, skb, ub, src, dst,
> > > + &ub->rcast.dst_cache);
> > > + local_bh_enable();
> > > + return err;
> > > + }
> > >
> > > /* Replicast, send an skb to each configured IP address */
> > > list_for_each_entry_rcu(rcast, &ub->rcast.list, list) {
> > > @@ -259,6 +264,7 @@ static int tipc_udp_send_msg(struct net *net, struct sk_buff *skb,
> > > err = 0;
> > > out:
> > > kfree_skb(skb);
> > > + local_bh_enable();
> > > return err;
> > > }
> > >
> > > --
> > > 2.7.4
> > >
> > > --
> > > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> > > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@...glegroups.com.
> > > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/1565595162-1383-4-git-send-email-ying.xue%40windriver.com.
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