[syzbot] linux-next test error: general protection fault in xfrm_policy_lookup_bytype

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syzbot

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Nov 21, 2022, 8:47:39 AM11/21/22
to da...@davemloft.net, edum...@google.com, her...@gondor.apana.org.au, ku...@kernel.org, linux-...@vger.kernel.org, linux...@vger.kernel.org, net...@vger.kernel.org, pab...@redhat.com, s...@canb.auug.org.au, steffen....@secunet.com, syzkall...@googlegroups.com
Hello,

syzbot found the following issue on:

HEAD commit: e4cd8d3ff7f9 Add linux-next specific files for 20221121
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1472370d880000
kernel config: https://syzkaller.appspot.com/x/.config?x=a0ebedc6917bacc1
dashboard link: https://syzkaller.appspot.com/bug?extid=bfb2bee01b9c01fff864
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b59eb967701d/disk-e4cd8d3f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/37a7b43e6e84/vmlinux-e4cd8d3f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ebfb0438e6a2/bzImage-e4cd8d3f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bfb2be...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000019: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000000c8-0x00000000000000cf]
CPU: 0 PID: 5295 Comm: kworker/0:3 Not tainted 6.1.0-rc5-next-20221121-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Workqueue: ipv6_addrconf addrconf_dad_work
RIP: 0010:xfrm_policy_lookup_bytype.cold+0x1c/0x54 net/xfrm/xfrm_policy.c:2139
Code: 80 44 28 8e e8 9a 88 37 fa e9 28 e7 7b fe e8 c0 25 7a f7 49 8d bf cc 00 00 00 b8 ff ff 37 00 48 89 fa 48 c1 e0 2a 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 1c 41
RSP: 0018:ffffc90003cdf1e0 EFLAGS: 00010203
RAX: dffffc0000000000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: 0000000000000019 RSI: ffffffff8a068150 RDI: 00000000000000cc
RBP: 0000000000000000 R08: 0000000000000007 R09: fffffffffffff000
R10: 0000000000000000 R11: 0000000000000005 R12: 0000000000000000
R13: ffff88802ae78000 R14: ffffed10055cf2ff R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb5cb893300 CR3: 00000000714fb000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
xfrm_policy_lookup net/xfrm/xfrm_policy.c:2151 [inline]
xfrm_bundle_lookup net/xfrm/xfrm_policy.c:2958 [inline]
xfrm_lookup_with_ifid+0x39b/0x20f0 net/xfrm/xfrm_policy.c:3099
xfrmi_xmit2 net/xfrm/xfrm_interface.c:404 [inline]
xfrmi_xmit+0x3c7/0x1b90 net/xfrm/xfrm_interface.c:521
__netdev_start_xmit include/linux/netdevice.h:4859 [inline]
netdev_start_xmit include/linux/netdevice.h:4873 [inline]
xmit_one net/core/dev.c:3583 [inline]
dev_hard_start_xmit+0x1c2/0x990 net/core/dev.c:3599
__dev_queue_xmit+0x2cdf/0x3ba0 net/core/dev.c:4249
dev_queue_xmit include/linux/netdevice.h:3029 [inline]
neigh_connected_output+0x3c4/0x520 net/core/neighbour.c:1600
neigh_output include/net/neighbour.h:546 [inline]
ip6_finish_output2+0x56c/0x1530 net/ipv6/ip6_output.c:134
__ip6_finish_output net/ipv6/ip6_output.c:195 [inline]
ip6_finish_output+0x694/0x1170 net/ipv6/ip6_output.c:206
NF_HOOK_COND include/linux/netfilter.h:291 [inline]
ip6_output+0x1f1/0x540 net/ipv6/ip6_output.c:227
dst_output include/net/dst.h:444 [inline]
NF_HOOK include/linux/netfilter.h:302 [inline]
ndisc_send_skb+0xa63/0x1740 net/ipv6/ndisc.c:508
ndisc_send_rs+0x132/0x6f0 net/ipv6/ndisc.c:718
addrconf_dad_completed+0x37a/0xda0 net/ipv6/addrconf.c:4248
addrconf_dad_begin net/ipv6/addrconf.c:4014 [inline]
addrconf_dad_work+0x820/0x12d0 net/ipv6/addrconf.c:4116
process_one_work+0x9bf/0x1710 kernel/workqueue.c:2289
worker_thread+0x669/0x1090 kernel/workqueue.c:2436
kthread+0x2e8/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:xfrm_policy_lookup_bytype.cold+0x1c/0x54 net/xfrm/xfrm_policy.c:2139
Code: 80 44 28 8e e8 9a 88 37 fa e9 28 e7 7b fe e8 c0 25 7a f7 49 8d bf cc 00 00 00 b8 ff ff 37 00 48 89 fa 48 c1 e0 2a 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 1c 41
RSP: 0018:ffffc90003cdf1e0 EFLAGS: 00010203
RAX: dffffc0000000000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: 0000000000000019 RSI: ffffffff8a068150 RDI: 00000000000000cc
RBP: 0000000000000000 R08: 0000000000000007 R09: fffffffffffff000
R10: 0000000000000000 R11: 0000000000000005 R12: 0000000000000000
R13: ffff88802ae78000 R14: ffffed10055cf2ff R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb5cb893300 CR3: 00000000714fb000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 1 bytes skipped:
0: 44 28 8e e8 9a 88 37 sub %r9b,0x37889ae8(%rsi)
7: fa cli
8: e9 28 e7 7b fe jmpq 0xfe7be735
d: e8 c0 25 7a f7 callq 0xf77a25d2
12: 49 8d bf cc 00 00 00 lea 0xcc(%r15),%rdi
19: b8 ff ff 37 00 mov $0x37ffff,%eax
1e: 48 89 fa mov %rdi,%rdx
21: 48 c1 e0 2a shl $0x2a,%rax
25: 48 c1 ea 03 shr $0x3,%rdx
* 29: 0f b6 14 02 movzbl (%rdx,%rax,1),%edx <-- trapping instruction
2d: 48 89 f8 mov %rdi,%rax
30: 83 e0 07 and $0x7,%eax
33: 83 c0 03 add $0x3,%eax
36: 38 d0 cmp %dl,%al
38: 7c 04 jl 0x3e
3a: 84 d2 test %dl,%dl
3c: 75 1c jne 0x5a
3e: 41 rex.B


---
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Sabrina Dubroca

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Nov 21, 2022, 10:08:27 AM11/21/22
to steffen....@secunet.com, syzbot, da...@davemloft.net, edum...@google.com, her...@gondor.apana.org.au, ku...@kernel.org, linux-...@vger.kernel.org, linux...@vger.kernel.org, net...@vger.kernel.org, pab...@redhat.com, s...@canb.auug.org.au, syzkall...@googlegroups.com
2022-11-21, 05:47:38 -0800, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: e4cd8d3ff7f9 Add linux-next specific files for 20221121
> git tree: linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=1472370d880000
> kernel config: https://syzkaller.appspot.com/x/.config?x=a0ebedc6917bacc1
> dashboard link: https://syzkaller.appspot.com/bug?extid=bfb2bee01b9c01fff864
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/b59eb967701d/disk-e4cd8d3f.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/37a7b43e6e84/vmlinux-e4cd8d3f.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/ebfb0438e6a2/bzImage-e4cd8d3f.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+bfb2be...@syzkaller.appspotmail.com
>
> general protection fault, probably for non-canonical address 0xdffffc0000000019: 0000 [#1] PREEMPT SMP KASAN
> KASAN: null-ptr-deref in range [0x00000000000000c8-0x00000000000000cf]
> CPU: 0 PID: 5295 Comm: kworker/0:3 Not tainted 6.1.0-rc5-next-20221121-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
> Workqueue: ipv6_addrconf addrconf_dad_work
> RIP: 0010:xfrm_policy_lookup_bytype.cold+0x1c/0x54 net/xfrm/xfrm_policy.c:2139

That's the printk at the end of the function, when
xfrm_policy_lookup_bytype returns NULL. It seems to have snuck into
commit c39f95aaf6d1 ("xfrm: Fix oops in __xfrm_state_delete()"), we
can just remove it:

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 3a203c59a11b..e392d8d05e0c 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -2135,9 +2135,6 @@ static struct xfrm_policy *xfrm_policy_lookup_bytype(struct net *net, u8 type,
fail:
rcu_read_unlock();

- if (!IS_ERR(ret))
- printk("xfrm_policy_lookup_bytype: policy if_id %d, wanted if_id %d\n", ret->if_id, if_id);
-
return ret;
--
Sabrina

Steffen Klassert

unread,
Nov 21, 2022, 12:15:17 PM11/21/22
to Sabrina Dubroca, syzbot, da...@davemloft.net, edum...@google.com, her...@gondor.apana.org.au, ku...@kernel.org, linux-...@vger.kernel.org, linux...@vger.kernel.org, net...@vger.kernel.org, pab...@redhat.com, s...@canb.auug.org.au, syzkall...@googlegroups.com
Hm, this was not in the original patch. Maybe my tree was not
clean when I applied it. Do you want to send a patch, or should
I just remove it?

Sabrina Dubroca

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Nov 21, 2022, 4:42:59 PM11/21/22
to Steffen Klassert, syzbot, da...@davemloft.net, edum...@google.com, her...@gondor.apana.org.au, ku...@kernel.org, linux-...@vger.kernel.org, linux...@vger.kernel.org, net...@vger.kernel.org, pab...@redhat.com, s...@canb.auug.org.au, syzkall...@googlegroups.com
Go ahead, I guess it's more convenient for you.

--
Sabrina

Steffen Klassert

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Nov 22, 2022, 1:27:01 AM11/22/22
to Sabrina Dubroca, syzbot, da...@davemloft.net, edum...@google.com, her...@gondor.apana.org.au, ku...@kernel.org, linux-...@vger.kernel.org, linux...@vger.kernel.org, net...@vger.kernel.org, pab...@redhat.com, s...@canb.auug.org.au, syzkall...@googlegroups.com
I just did a forced push to remove that hunk.

Thanks!

Dmitry Vyukov

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Nov 25, 2022, 5:22:33 AM11/25/22
to Steffen Klassert, Sabrina Dubroca, syzbot, da...@davemloft.net, edum...@google.com, her...@gondor.apana.org.au, ku...@kernel.org, linux-...@vger.kernel.org, linux...@vger.kernel.org, net...@vger.kernel.org, pab...@redhat.com, s...@canb.auug.org.au, syzkall...@googlegroups.com
Let's tell syzbot about the fix, so that it reports similarly looking
crashes in future:

#syz fix: xfrm: Fix oops in __xfrm_state_delete()
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