BUG: using smp_processor_id() in preemptible [ADDR] code: syz-executor

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: ee7dd773 sis900: remove TxIDLE
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17ceb9a9a00000
kernel config: https://syzkaller.appspot.com/x/.config?x=7ac9edef4d37e5fb
dashboard link: https://syzkaller.appspot.com/bug?extid=1a68504d96cd17b33a05
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=119b2a13a00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13127bada00000

The bug was bisected to:

commit 52dfae5c85a4c1078e9f1d5e8947d4a25f73dd81
Author: Jon Maloy <jon....@ericsson.com>
Date: Thu Mar 22 19:42:52 2018 +0000

tipc: obtain node identity from interface by default

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=160ad903a00000
final crash: https://syzkaller.appspot.com/x/report.txt?x=150ad903a00000
console output: https://syzkaller.appspot.com/x/log.txt?x=110ad903a00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+1a6850...@syzkaller.appspotmail.com
Fixes: 52dfae5c85a4 ("tipc: obtain node identity from interface by default")

Started in network mode
Own node identity 7f000001, cluster identity 4711
New replicast peer: 172.20.20.22
check_preemption_disabled: 3 callbacks suppressed
BUG: using smp_processor_id() in preemptible [00000000] code:
syz-executor834/8612
caller is dst_cache_get+0x3d/0xb0 net/core/dst_cache.c:68
CPU: 0 PID: 8612 Comm: syz-executor834 Not tainted 5.2.0-rc6+ #48
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x172/0x1f0 lib/dump_stack.c:113
check_preemption_disabled lib/smp_processor_id.c:47 [inline]
debug_smp_processor_id+0x251/0x280 lib/smp_processor_id.c:57
dst_cache_get+0x3d/0xb0 net/core/dst_cache.c:68
tipc_udp_xmit.isra.0+0xc4/0xb80 net/tipc/udp_media.c:164
tipc_udp_send_msg+0x29a/0x4b0 net/tipc/udp_media.c:254
tipc_bearer_xmit_skb+0x16c/0x360 net/tipc/bearer.c:503
tipc_enable_bearer+0xabe/0xd20 net/tipc/bearer.c:328
__tipc_nl_bearer_enable+0x2de/0x3a0 net/tipc/bearer.c:899
tipc_nl_bearer_enable+0x23/0x40 net/tipc/bearer.c:907
genl_family_rcv_msg+0x74b/0xf90 net/netlink/genetlink.c:629
genl_rcv_msg+0xca/0x16c net/netlink/genetlink.c:654
netlink_rcv_skb+0x177/0x450 net/netlink/af_netlink.c:2477
genl_rcv+0x29/0x40 net/netlink/genetlink.c:665
netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
netlink_unicast+0x531/0x710 net/netlink/af_netlink.c:1328
netlink_sendmsg+0x8ae/0xd70 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:646 [inline]
sock_sendmsg+0xd7/0x130 net/socket.c:665
___sys_sendmsg+0x803/0x920 net/socket.c:2286
__sys_sendmsg+0x105/0x1d0 net/socket.c:2324
__do_sys_sendmsg net/socket.c:2333 [inline]
__se_sys_sendmsg net/socket.c:2331 [inline]
__x64_sys_sendmsg+0x78/0xb0 net/socket.c:2331
do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x444679
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
RSP: 002b:00007fff0201a8b8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000444679
RDX: 0000000000000000 RSI: 0000000020000580 RDI: 0000000000000003
RBP: 00000000006cf018 R08: 0000000000000001 R09: 00000000004002e0
R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000402320
R13: 00000000004023b0 R14: 0000000000000000 R15: 0000000000


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

[Dmitry Vyukov]

On Sun, Jun 30, 2019 at 7:19 AM Hillf Danton <hda...@sina.com> wrote:
>
>
> Hello,
>
> On Sat, 29 Jun 2019 08:47:06 -0700 (PDT)

> > syzbot found the following crash on:
> >
> > HEAD commit: ee7dd773 sis900: remove TxIDLE
> > git tree: net-next
> > console output: https://syzkaller.appspot.com/x/log.txt?x=17ceb9a9a00000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=7ac9edef4d37e5fb
> > dashboard link: https://syzkaller.appspot.com/bug?extid=1a68504d96cd17b33a05
> > compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=119b2a13a00000
> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13127bada00000
> >
> > The bug was bisected to:
>

> Hm... I doubt it is e9c1a793210f ("tipc: add dst_cache support for udp media")
> based on one of the lines dumped:
>
> > tipc_udp_xmit.isra.0+0xc4/0xb80 net/tipc/udp_media.c:164
>
>
> And getting the local bottom half disabled looks like a teaspoon of
> cough syrup.
> ---
>
> --- 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,
> + 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;
> }
>
> --

>
> > commit 52dfae5c85a4c1078e9f1d5e8947d4a25f73dd81
> > Author: Jon Maloy <jon....@ericsson.com>
> > Date: Thu Mar 22 19:42:52 2018 +0000
> >
> > tipc: obtain node identity from interface by default

What is the fate of this fix?
There is also another fix for this pending for half a year as far as I can tell.

This is one of the top crashes and it prevents most other kernel
testing from happening. All kernels just crash on this right away.

> --
> 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-bug...@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/000000000000a40746058c784ef3%40google.com.
> For more options, visit https://groups.google.com/d/optout.

[Dmitry Vyukov]

/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\

+jmaloy new email address

[Tetsuo Handa]

Arrived at net.git as commit 1378817486d6860f.

#syz fix: tipc: block BH before using dst_cache