Re: Fwd: UBSAN: index 1 is out of range for type 'xen_netif_rx_sring_entry [1]'

[Juergen Gross <jgross@suse.com>]

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On 23.07.23 02:06, Nathan Chancellor wrote:
> On Sat, Jul 22, 2023 at 07:21:05AM +0700, Bagas Sanjaya wrote:
>> Hi,
>>
>> I notice a regression report on Bugzilla [1]. Quoting from it:
>>
>>> Hi Kernel Team,
>>>
>>> I rebuild today latest version from mainline repo.
>>> And i notice issue regarding xen-netfront.c.
>>>
>>> Error:
>>> [    3.477400] ================================================================================
>>> [    3.477633] UBSAN: array-index-out-of-bounds in drivers/net/xen-netfront.c:1291:3
>>> [    3.477858] index 1 is out of range for type 'xen_netif_rx_sring_entry [1]'
>>> [    3.478085] CPU: 0 PID: 700 Comm: NetworkManager Not tainted 6.5.0-rc2-1-generation1 #3
>>> [    3.478088] Hardware name: Intel Corporation W2600CR/W2600CR, BIOS SE5C600.86B.02.06.0007.082420181029 01/13/2022
>>> [    3.478090] Call Trace:
>>> [    3.478092]  <IRQ>
>>> [    3.478097]  dump_stack_lvl+0x48/0x70
>>> [    3.478105]  dump_stack+0x10/0x20
>>> [    3.478107]  __ubsan_handle_out_of_bounds+0xc6/0x110
>>> [    3.478114]  xennet_poll+0xa94/0xac0
>>> [    3.478118]  ? generic_smp_call_function_single_interrupt+0x13/0x20
>>> [    3.478125]  __napi_poll+0x33/0x200
>>> [    3.478131]  net_rx_action+0x181/0x2e0
>>> [    3.478135]  __do_softirq+0xd9/0x346
>>> [    3.478139]  do_softirq.part.0+0x41/0x80
>>> [    3.478144]  </IRQ>
>>> [    3.478145]  <TASK>
>>> [    3.478146]  __local_bh_enable_ip+0x72/0x80
>>> [    3.478149]  _raw_spin_unlock_bh+0x1d/0x30
>>> [    3.478151]  xennet_open+0x75/0x160
>>> [    3.478154]  __dev_open+0x105/0x1d0
>>> [    3.478156]  __dev_change_flags+0x1b5/0x230
>>> [    3.478158]  dev_change_flags+0x27/0x80
>>> [    3.478160]  do_setlink+0x3d2/0x12b0
>>> [    3.478164]  ? __nla_validate_parse+0x5b/0xdb0
>>> [    3.478169]  __rtnl_newlink+0x6f6/0xb10
>>> [    3.478173]  ? rtnl_newlink+0x2f/0x80
>>> [    3.478177]  rtnl_newlink+0x48/0x80
>>> [    3.478180]  rtnetlink_rcv_msg+0x170/0x430
>>> [    3.478183]  ? fib6_clean_node+0xad/0x190
>>> [    3.478188]  ? __pfx_rtnetlink_rcv_msg+0x10/0x10
>>> [    3.478191]  netlink_rcv_skb+0x5d/0x110
>>> [    3.478195]  rtnetlink_rcv+0x15/0x30
>>> [    3.478198]  netlink_unicast+0x247/0x390
>>> [    3.478200]  netlink_sendmsg+0x25e/0x4e0
>>> [    3.478202]  sock_sendmsg+0xaf/0xc0
>>> [    3.478204]  ____sys_sendmsg+0x2a9/0x350
>>> [    3.478206]  ___sys_sendmsg+0x9a/0xf0
>>> [    3.478212]  ? _copy_from_iter+0x80/0x4a0
>>> [    3.478217]  __sys_sendmsg+0x89/0xf0
>>> [    3.478220]  __x64_sys_sendmsg+0x1d/0x30
>>> [    3.478222]  do_syscall_64+0x5c/0x90
>>> [    3.478226]  ? do_syscall_64+0x68/0x90
>>> [    3.478228]  ? ksys_write+0xe6/0x100
>>> [    3.478232]  ? exit_to_user_mode_prepare+0x49/0x220
>>> [    3.478236]  ? syscall_exit_to_user_mode+0x1b/0x50
>>> [    3.478240]  ? do_syscall_64+0x68/0x90
>>> [    3.478242]  ? do_syscall_64+0x68/0x90
>>> [    3.478243]  ? irqentry_exit_to_user_mode+0x9/0x30
>>> [    3.478246]  ? irqentry_exit+0x43/0x50
>>> [    3.478248]  ? sysvec_xen_hvm_callback+0x4b/0xd0
>>> [    3.478250]  entry_SYSCALL_64_after_hwframe+0x6e/0xd8
>>> [    3.478253] RIP: 0033:0x7f973c244e4d
>>> [    3.478268] Code: 28 89 54 24 1c 48 89 74 24 10 89 7c 24 08 e8 ca ee ff ff 8b 54 24 1c 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 33 44 89 c7 48 89 44 24 08 e8 fe ee ff ff 48
>>> [    3.478270] RSP: 002b:00007fff4777f470 EFLAGS: 00000293 ORIG_RAX: 000000000000002e
>>> [    3.478273] RAX: ffffffffffffffda RBX: 00005583087c6480 RCX: 00007f973c244e4d
>>> [    3.478274] RDX: 0000000000000000 RSI: 00007fff4777f4c0 RDI: 000000000000000c
>>> [    3.478276] RBP: 00007fff4777f4c0 R08: 0000000000000000 R09: 0000000000000000
>>> [    3.478277] R10: 0000000000000000 R11: 0000000000000293 R12: 00005583087c6480
>>> [    3.478279] R13: 00007fff4777f668 R14: 00007fff4777f65c R15: 0000000000000000
>>> [    3.478283]  </TASK>
>>> [    3.478284] ================================================================================
>>> [    3.685513] ================================================================================
>>> [    3.685751] UBSAN: array-index-out-of-bounds in drivers/net/xen-netfront.c:485:7
>>> [    3.686111] index 1 is out of range for type 'xen_netif_tx_sring_entry [1]'
>>> [    3.686379] CPU: 1 PID: 697 Comm: avahi-daemon Not tainted 6.5.0-rc2-1-generation1 #3
>>> [    3.686381] Hardware name: Intel Corporation W2600CR/W2600CR, BIOS SE5C600.86B.02.06.0007.082420181029 01/13/2022
>>> [    3.686385] Call Trace:
>>> [    3.686388]  <TASK>
>>> [    3.686391]  dump_stack_lvl+0x48/0x70
>>> [    3.686399]  dump_stack+0x10/0x20
>>> [    3.686399]  __ubsan_handle_out_of_bounds+0xc6/0x110
>>> [    3.686403]  xennet_tx_setup_grant+0x1f7/0x230
>>> [    3.686403]  ? __pfx_xennet_tx_setup_grant+0x10/0x10
>>> [    3.686403]  gnttab_foreach_grant_in_range+0x5c/0x100
>>> [    3.686415]  xennet_start_xmit+0x428/0x990
>>> [    3.686415]  ? kmem_cache_alloc_node+0x1b1/0x3b0
>>> [    3.686415]  dev_hard_start_xmit+0x68/0x1e0
>>> [    3.686415]  sch_direct_xmit+0x10b/0x350
>>> [    3.686415]  __dev_queue_xmit+0x512/0xda0
>>> [    3.686439]  ? ___neigh_create+0x6cb/0x970
>>> [    3.686439]  neigh_resolve_output+0x118/0x1e0
>>> [    3.686446]  ip_finish_output2+0x181/0x540
>>> [    3.686450]  ? netif_rx_internal+0x46/0x140
>>> [    3.686456]  __ip_finish_output+0xb6/0x180
>>> [    3.686456]  ? dev_loopback_xmit+0x86/0x110
>>> [    3.686456]  ip_finish_output+0x29/0x100
>>> [    3.686456]  ip_mc_output+0x95/0x2e0
>>> [    3.686456]  ? __pfx_ip_finish_output+0x10/0x10
>>> [    3.686456]  ip_send_skb+0x9f/0xb0
>>> [    3.686456]  udp_send_skb+0x158/0x380
>>> [    3.686475]  udp_sendmsg+0xb84/0xf20
>>> [    3.686475]  ? do_sys_poll+0x3a1/0x5f0
>>> [    3.686483]  ? __pfx_ip_generic_getfrag+0x10/0x10
>>> [    3.686483]  inet_sendmsg+0x76/0x80
>>> [    3.686483]  ? inet_sendmsg+0x76/0x80
>>> [    3.686483]  sock_sendmsg+0xa8/0xc0
>>> [    3.686483]  ? _copy_from_user+0x30/0xa0
>>> [    3.686483]  ____sys_sendmsg+0x2a9/0x350
>>> [    3.686483]  ___sys_sendmsg+0x9a/0xf0
>>> [    3.686483]  __sys_sendmsg+0x89/0xf0
>>> [    3.686483]  __x64_sys_sendmsg+0x1d/0x30
>>> [    3.686483]  do_syscall_64+0x5c/0x90
>>> [    3.686483]  ? exit_to_user_mode_prepare+0x49/0x220
>>> [    3.686483]  ? syscall_exit_to_user_mode+0x1b/0x50
>>> [    3.686483]  ? do_syscall_64+0x68/0x90
>>> [    3.686483]  ? syscall_exit_to_user_mode+0x1b/0x50
>>> [    3.686483]  ? do_syscall_64+0x68/0x90
>>> [    3.686483]  entry_SYSCALL_64_after_hwframe+0x6e/0xd8
>>> [    3.686483] RIP: 0033:0x7ff365942e13
>>> [    3.686483] Code: 8b 15 b9 a1 00 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b8 0f 1f 00 64 8b 04 25 18 00 00 00 85 c0 75 14 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 55 c3 0f 1f 40 00 48 83 ec 28 89 54 24 1c 48
>>> [    3.686483] RSP: 002b:00007ffc7bf1ca78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
>>> [    3.686483] RAX: ffffffffffffffda RBX: 00005596bd24c900 RCX: 00007ff365942e13
>>> [    3.686483] RDX: 0000000000000000 RSI: 00007ffc7bf1cb30 RDI: 000000000000000c
>>> [    3.686483] RBP: 000000000000000c R08: 0000000000000004 R09: 0000000000000019
>>> [    3.686483] R10: 00007ff365a1ca94 R11: 0000000000000246 R12: 00007ffc7bf1cb30
>>> [    3.686483] R13: 0000000000000002 R14: 00005596bd235f9c R15: 0000000000000000
>>> [    3.686483]  </TASK>
>>> [    3.686483] ================================================================================
>>> [    3.686858] ================================================================================
>>> [    3.687190] UBSAN: array-index-out-of-bounds in drivers/net/xen-netfront.c:413:4
>>> [    3.687501] index 1 is out of range for type 'xen_netif_tx_sring_entry [1]'
>>> [    3.687800] CPU: 18 PID: 0 Comm: swapper/18 Not tainted 6.5.0-rc2-1-generation1 #3
>>> [    3.687804] Hardware name: Intel Corporation W2600CR/W2600CR, BIOS SE5C600.86B.02.06.0007.082420181029 01/13/2022
>>> [    3.687806] Call Trace:
>>> [    3.687808]  <IRQ>
>>> [    3.687812]  dump_stack_lvl+0x48/0x70
>>> [    3.687819]  dump_stack+0x10/0x20
>>> [    3.687821]  __ubsan_handle_out_of_bounds+0xc6/0x110
>>> [    3.687827]  xennet_tx_buf_gc+0x34a/0x440
>>> [    3.687831]  xennet_handle_tx.constprop.0+0x49/0x90
>>> [    3.687834]  xennet_tx_interrupt+0x32/0x70
>>> [    3.687837]  __handle_irq_event_percpu+0x4f/0x1b0
>>> [    3.687842]  handle_irq_event+0x39/0x80
>>> [    3.687846]  handle_edge_irq+0x8c/0x230
>>> [    3.687849]  handle_irq_desc+0x40/0x60
>>> [    3.687851]  generic_handle_irq+0x1f/0x30
>>> [    3.687854]  handle_irq_for_port+0x8e/0x180
>>> [    3.687858]  ? _raw_spin_unlock_irqrestore+0x11/0x60
>>> [    3.687861]  __evtchn_fifo_handle_events+0x221/0x330
>>> [    3.687866]  evtchn_fifo_handle_events+0xe/0x20
>>> [    3.687869]  __xen_evtchn_do_upcall+0x72/0xd0
>>> [    3.687873]  xen_hvm_evtchn_do_upcall+0xe/0x20
>>> [    3.687876]  __sysvec_xen_hvm_callback+0x53/0x70
>>> [    3.687880]  sysvec_xen_hvm_callback+0x8d/0xd0
>>> [    3.687884]  </IRQ>
>>> [    3.687885]  <TASK>
>>> [    3.687886]  asm_sysvec_xen_hvm_callback+0x1b/0x20
>>> [    3.687891] RIP: 0010:pv_native_safe_halt+0xb/0x10
>>> [    3.687896] Code: 0b 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 eb 07 0f 00 2d 49 cc 33 00 fb f4 <c3> cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55
>>> [    3.687898] RSP: 0000:ffffad85c0147e08 EFLAGS: 00000246
>>> [    3.687901] RAX: ffffffffa00d39a0 RBX: 0000000000000002 RCX: 0000000000000000
>>> [    3.687902] RDX: 0000000000000002 RSI: ffffffffa14d28e0 RDI: ffff920446abda00
>>> [    3.687904] RBP: ffffad85c0147e18 R08: 0000000000000000 R09: 0000000000000000
>>> [    3.687905] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000002
>>> [    3.687906] R13: 0000000000000002 R14: 0000000000000002 R15: ffffffffa14d29c8
>>> [    3.687909]  ? __pfx_intel_idle_hlt+0x10/0x10
>>> [    3.687913]  ? intel_idle_hlt+0xc/0x40
>>> [    3.687916]  cpuidle_enter_state+0xa0/0x730
>>> [    3.687920]  cpuidle_enter+0x2e/0x50
>>> [    3.687924]  call_cpuidle+0x23/0x60
>>> [    3.687928]  do_idle+0x207/0x260
>>> [    3.687932]  cpu_startup_entry+0x1d/0x20
>>> [    3.687934]  start_secondary+0x129/0x160
>>> [    3.687939]  secondary_startup_64_no_verify+0x17e/0x18b
>>> [    3.687945]  </TASK>
>>> [    3.687946] ================================================================================
>>> [    4.624607] bridge: filtering via arp/ip/ip6tables is no longer available by default. Update your scripts to load br_netfilter if you need this.
>>> [    4.629153] Bridge firewalling registered
>>> [    4.745355] Initializing XFRM netlink socket
>>> [    4.794107] loop8: detected capacity change from 0 to 8
>>> [    7.104544] rfkill: input handler disabled
>>> [   26.445163] ================================================================================
>>> [   26.445171] UBSAN: array-index-out-of-bounds in drivers/net/xen-netfront.c:807:4
>>> [   26.445175] index 109 is out of range for type 'xen_netif_tx_sring_entry [1]'
>>> [   26.445178] CPU: 8 PID: 1729 Comm: sshd Not tainted 6.5.0-rc2-1-generation1 #3
>>> [   26.445180] Hardware name: Intel Corporation W2600CR/W2600CR, BIOS SE5C600.86B.02.06.0007.082420181029 01/13/2022
>>> [   26.445181] Call Trace:
>>> [   26.445185]  <TASK>
>>> [   26.445185]  dump_stack_lvl+0x48/0x70
>>> [   26.445185]  dump_stack+0x10/0x20
>>> [   26.445200]  __ubsan_handle_out_of_bounds+0xc6/0x110
>>> [   26.445206]  xennet_start_xmit+0x932/0x990
>>> [   26.445211]  dev_hard_start_xmit+0x68/0x1e0
>>> [   26.445216]  sch_direct_xmit+0x10b/0x350
>>> [   26.445220]  __dev_queue_xmit+0x512/0xda0
>>> [   26.445224]  ip_finish_output2+0x261/0x540
>>> [   26.445225]  __ip_finish_output+0xb6/0x180
>>> [   26.445225]  ip_finish_output+0x29/0x100
>>> [   26.445234]  ip_output+0x73/0x120
>>> [   26.445234]  ? __pfx_ip_finish_output+0x10/0x10
>>> [   26.445238]  ip_local_out+0x61/0x70
>>> [   26.445238]  __ip_queue_xmit+0x18d/0x470
>>> [   26.445238]  ip_queue_xmit+0x15/0x30
>>> [   26.445238]  __tcp_transmit_skb+0xb39/0xcc0
>>> [   26.445238]  tcp_write_xmit+0x595/0x1570
>>> [   26.445238]  ? _copy_from_iter+0x80/0x4a0
>>> [   26.445256]  __tcp_push_pending_frames+0x37/0x110
>>> [   26.445259]  tcp_push+0x123/0x190
>>> [   26.445260]  tcp_sendmsg_locked+0xafe/0xed0
>>> [   26.445264]  tcp_sendmsg+0x2c/0x50
>>> [   26.445268]  inet_sendmsg+0x42/0x80
>>> [   26.445268]  sock_write_iter+0x160/0x180
>>> [   26.445274]  vfs_write+0x397/0x440
>>> [   26.445274]  ksys_write+0xc9/0x100
>>> [   26.445274]  __x64_sys_write+0x19/0x30
>>> [   26.445274]  do_syscall_64+0x5c/0x90
>>> [   26.445287]  ? syscall_exit_to_user_mode+0x1b/0x50
>>> [   26.445290]  ? do_syscall_64+0x68/0x90
>>> [   26.445290]  ? do_syscall_64+0x68/0x90
>>> [   26.445294]  ? do_syscall_64+0x68/0x90
>>> [   26.445294]  ? syscall_exit_to_user_mode+0x1b/0x50
>>> [   26.445298]  ? do_syscall_64+0x68/0x90
>>> [   26.445300]  ? exc_page_fault+0x94/0x1b0
>>> [   26.445302]  entry_SYSCALL_64_after_hwframe+0x6e/0xd8
>>> [   26.445306] RIP: 0033:0x7f26c4c3d473
>>> [   26.445318] Code: 8b 15 21 2a 0e 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 64 8b 04 25 18 00 00 00 85 c0 75 14 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 55 c3 0f 1f 40 00 48 83 ec 28 48 89 54 24 18
>>> [   26.445321] RSP: 002b:00007ffdee7b5528 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
>>> [   26.445321] RAX: ffffffffffffffda RBX: 0000000000000700 RCX: 00007f26c4c3d473
>>> [   26.445321] RDX: 0000000000000700 RSI: 000055567032e230 RDI: 0000000000000004
>>> [   26.445321] RBP: 0000555670313d70 R08: fffffffffffffff0 R09: 0000000000000000
>>> [   26.445321] R10: 0000000000000000 R11: 0000000000000246 R12: 000055566fcb2768
>>> [   26.445321] R13: 0000000000000000 R14: 0000000000000004 R15: 000055566fc67a80
>>> [   26.445332]  </TASK>
>>> [   26.445333] ================================================================================
>>
>> See Bugzilla for the full thread and attached dmesg.
>>
>> Anyway, I'm adding it to regzbot:
>>
>> #regzbot introduced: 8446066bf8c1f9f https://bugzilla.kernel.org/show_bug.cgi?id=217693
>>
>> Thanks.
>>
>> [1]: https://bugzilla.kernel.org/show_bug.cgi?id=217693
> 
> I doubt it is 8446066bf8c1f9f that causes this. Based on the comment
> next to the 'ring[1]' in DEFINE_RING_TYPES() in
> include/xen/interface/io/ring.h, this is probably caused/exposed by
> commit df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3") in
> 6.5-rc1, which causes that array to no longer be a flexible array but an
> array with one element, which would cause UBSAN to complain about an
> array access past index one. Adding Kees and Gustavo.

I agree.

> 
> Unfortunately, it seems this file is vendored from Xen, so I assume it
> would need to be fixed there then pulled into Linux:
> 
> https://github.com/xen-project/xen/tree/master/xen/include/public/io/ring.h

No, I don't think it will be possible to change this in the Xen tree easily.

Especially the public Xen headers are meant to be compatible with a large
variety of compilers, including rather old ones.

This means that ring[1] can't be easily swapped with ring[], as that would
cause compile time errors with some compilers.

Just modifying the Linux side header is an option, though, as we don't need
the same wide range of supported compilers as Xen.

I'll send a patch for that purpose.


Juergen


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