[syzbot] general protection fault in em_cmp_match

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Dec 14, 2022, 7:12:51 PM12/14/22
to da...@davemloft.net, edum...@google.com, j...@mojatatu.com, ji...@resnulli.us, ku...@kernel.org, linux-...@vger.kernel.org, net...@vger.kernel.org, pab...@redhat.com, syzkall...@googlegroups.com, xiyou.w...@gmail.com
Hello,

syzbot found the following issue on:

HEAD commit: 296a7b7eb792 Merge tag 'for-linus' of git://git.armlinux.o..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=173ee77d880000
kernel config: https://syzkaller.appspot.com/x/.config?x=4edf421741552bc3
dashboard link: https://syzkaller.appspot.com/bug?extid=4caeae4c7103813598ae
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=128f80ed880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16096513880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/44efe7c1185f/disk-296a7b7e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/22c2c707e34d/vmlinux-296a7b7e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9a8c92b56666/bzImage-296a7b7e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4caeae...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 1 PID: 154 Comm: kworker/1:2 Not tainted 6.1.0-rc8-syzkaller-00154-g296a7b7eb792 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Workqueue: ipv6_addrconf addrconf_dad_work
RIP: 0010:em_cmp_match+0x55/0x670 net/sched/em_cmp.c:25
Code: 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 b0 05 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 6b 08 4c 8d 7d 0a 4c 89 fa 48 c1 ea 03 <0f> b6 14 02 4c 89 f8 83 e0 07 83 c0 01 38 d0 7c 08 84 d2 0f 85 47
RSP: 0018:ffffc90002e4ec40 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff88801f5817c0 RCX: 0000000000000000
RDX: 0000000000000001 RSI: ffffffff87f06d8d RDI: ffff88801f5817c8
RBP: 0000000000000000 R08: 0000000000000004 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000001 R12: ffff8880719c9a00
R13: 0000000000000000 R14: 0000000000000000 R15: 000000000000000a
FS: 0000000000000000(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000080 CR3: 000000000c28e000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
tcf_em_match net/sched/ematch.c:492 [inline]
__tcf_em_tree_match+0x153/0x560 net/sched/ematch.c:518
tcf_em_tree_match include/net/pkt_cls.h:502 [inline]
basic_classify+0x206/0x330 net/sched/cls_basic.c:48
__tcf_classify net/sched/cls_api.c:1567 [inline]
tcf_classify+0x3ec/0xa40 net/sched/cls_api.c:1633
prio_classify net/sched/sch_prio.c:42 [inline]
prio_enqueue+0x3ab/0x790 net/sched/sch_prio.c:75
dev_qdisc_enqueue+0x46/0x390 net/core/dev.c:3785
__dev_xmit_skb net/core/dev.c:3874 [inline]
__dev_queue_xmit+0x2279/0x3ba0 net/core/dev.c:4222
dev_queue_xmit include/linux/netdevice.h:3008 [inline]
neigh_hh_output include/net/neighbour.h:530 [inline]
neigh_output include/net/neighbour.h:544 [inline]
ip_finish_output2+0x14e3/0x2180 net/ipv4/ip_output.c:228
__ip_finish_output net/ipv4/ip_output.c:306 [inline]
__ip_finish_output+0x396/0x650 net/ipv4/ip_output.c:288
ip_finish_output+0x31/0x280 net/ipv4/ip_output.c:316
NF_HOOK_COND include/linux/netfilter.h:291 [inline]
ip_output+0x1a3/0x320 net/ipv4/ip_output.c:430
dst_output include/net/dst.h:445 [inline]
ip_local_out+0xb3/0x1a0 net/ipv4/ip_output.c:126
iptunnel_xmit+0x67e/0x9f0 net/ipv4/ip_tunnel_core.c:82
geneve_xmit_skb drivers/net/geneve.c:996 [inline]
geneve_xmit+0x1318/0x4910 drivers/net/geneve.c:1108
__netdev_start_xmit include/linux/netdevice.h:4840 [inline]
netdev_start_xmit include/linux/netdevice.h:4854 [inline]
xmit_one net/core/dev.c:3590 [inline]
dev_hard_start_xmit+0x1c2/0x990 net/core/dev.c:3606
__dev_queue_xmit+0x2cdf/0x3ba0 net/core/dev.c:4256
dev_queue_xmit include/linux/netdevice.h:3008 [inline]
neigh_resolve_output net/core/neighbour.c:1571 [inline]
neigh_resolve_output+0x51b/0x840 net/core/neighbour.c:1551
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:445 [inline]
NF_HOOK include/linux/netfilter.h:302 [inline]
ndisc_send_skb+0xa63/0x1740 net/ipv6/ndisc.c:508
ndisc_send_ns+0xaa/0x130 net/ipv6/ndisc.c:666
addrconf_dad_work+0xbf4/0x12d0 net/ipv6/addrconf.c:4171
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:306
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:em_cmp_match+0x55/0x670 net/sched/em_cmp.c:25
Code: 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 b0 05 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 6b 08 4c 8d 7d 0a 4c 89 fa 48 c1 ea 03 <0f> b6 14 02 4c 89 f8 83 e0 07 83 c0 01 38 d0 7c 08 84 d2 0f 85 47
RSP: 0018:ffffc90002e4ec40 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff88801f5817c0 RCX: 0000000000000000
RDX: 0000000000000001 RSI: ffffffff87f06d8d RDI: ffff88801f5817c8
RBP: 0000000000000000 R08: 0000000000000004 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000001 R12: ffff8880719c9a00
R13: 0000000000000000 R14: 0000000000000000 R15: 000000000000000a
FS: 0000000000000000(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000080 CR3: 000000000c28e000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 48 89 fa mov %rdi,%rdx
3: 48 c1 ea 03 shr $0x3,%rdx
7: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1)
b: 0f 85 b0 05 00 00 jne 0x5c1
11: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
18: fc ff df
1b: 48 8b 6b 08 mov 0x8(%rbx),%rbp
1f: 4c 8d 7d 0a lea 0xa(%rbp),%r15
23: 4c 89 fa mov %r15,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 0f b6 14 02 movzbl (%rdx,%rax,1),%edx <-- trapping instruction
2e: 4c 89 f8 mov %r15,%rax
31: 83 e0 07 and $0x7,%eax
34: 83 c0 01 add $0x1,%eax
37: 38 d0 cmp %dl,%al
39: 7c 08 jl 0x43
3b: 84 d2 test %dl,%dl
3d: 0f .byte 0xf
3e: 85 .byte 0x85
3f: 47 rex.RXB


---
This report is generated by a bot. It may contain errors.
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syzbot can test patches for this issue, for details see:
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syzbot

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Dec 17, 2022, 4:57:16 PM12/17/22
to syzkall...@googlegroups.com, xiyou.w...@gmail.com
Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+4caeae...@syzkaller.appspotmail.com

Tested on:

commit: 1322dce2 fix ematch
git tree: https://github.com/congwang/linux.git net
console output: https://syzkaller.appspot.com/x/log.txt?x=140d4c20480000
kernel config: https://syzkaller.appspot.com/x/.config?x=4edf421741552bc3
dashboard link: https://syzkaller.appspot.com/bug?extid=4caeae4c7103813598ae
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Note: no patches were applied.
Note: testing is done by a robot and is best-effort only.
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