Re: Fwd: kernel tried to execute NX-protected page - exploit attempt? (uid: 0) (qbittorrent with tx-nocache-copy)

[Bagas Sanjaya]

Hi CM76,

On 24/10/2023 15:15, Bagas Sanjaya wrote:
> Hi,
> 
> I notice a regression report on Bugzilla [1]. Quoting from it:
> 
>> I believe this is also an issue with the Broadcom bnx2 drivers since it only seem to happen when I enable "tx-nocache-copy" in ethtool.  
>>
>> The issue started when I was running Mainline/stable Kernel v6.5.x on another machine, after google-ing a bit I landed on an article from redhat that pointed at the possibility of an issue caused by a failing hardware. I was renting the server, so I didn't bother to fill a bug report and assumed it was the server that was going bad. But then it happened again on my other server as soon as I switched the bittorrent client to the same I was using on that other server. I turned "tx-nocache-copy" off and ran mainline kernel v6.5 (on Ubuntu 23.04) for a day or two without issue. After that I switched the kernel back to Ubuntu's kernel (v6.2) and the server ran for a couple more days without issue. Two days ago I turned "tx-nocache-copy" on again out of curiosity (kernel v6.2), and the server didn't run into any issue with this setting set to on. This morning I upgraded to Ubuntu 23.10 that runs their version of Kernel v6.5. The kernel panicked and server rebooted a couple of hours later. 
>>
>>
>> The issue seem to be triggered with a certain configuration of applications, I've ran Mainline/stable kernel 6.5.x since its release (and before that v6.4.x) with the rtorrent bittorrent client and "tx-nocache-copy" turned on, the kernel didn't run into any issue for weeks until I switched to another bittorrent client (qbittorrent) last week. It doesn't seem to matter when it happens, the kernel can Opps when the client is downloading a single small sized torrent to when it's downloading multiple torrents at the same time. 
>>
>>
>> I tried to use the crash utiliy to get the backtrace but it doesn't seem to work correctly. I get "crash: invalid structure member offset: module_core_size FILE: kernel.c  LINE: 3781  FUNCTION: module_init()" when I try to load the kernel dump. 
>>
>> The kernel panic happens with 6.5.x Mainline/stable kernel as well as the 6.5 kernel that comes with ubuntu 23.10.
>>
>> The bittorrent clients run as systemd services with normal user privileges and "ProtectKernelModules=yes" "NoNewPrivileges=yes" set in the systemd service. 
>>
>> I joined the full dmesg as attachement, and I can send the kdump generated kernel dump file if needed. 
>>
>>
>> ------------------------
>> [12090.273551] kernel tried to execute NX-protected page - exploit attempt? (uid: 0)
>> [12090.273577] BUG: unable to handle page fault for address: ffff9441c9734458
>> [12090.273590] #PF: supervisor instruction fetch in kernel mode
>> [12090.273602] #PF: error_code(0x0011) - permissions violation
>> [12090.273614] PGD 157401067 P4D 157401067 PUD 23ffff067 PMD 108a81063 PTE 8000000109734063
>> [12090.273632] Oops: 0011 [#1] PREEMPT SMP PTI
>> [12090.273643] CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Not tainted 6.5.0-9-generic #9-Ubuntu
>> [12090.273658] Hardware name: Dell Inc. PowerEdge R210 II/03X6X0, BIOS 2.10.0 05/24/2018
>> [12090.273674] RIP: 0010:0xffff9441c9734458
>> [12090.273694] Code: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 <00> 00 00 00 00 00 00 00 58 44 73 c9 41 94 ff ff 00 00 00 00 00 00
>> [12090.273723] RSP: 0018:ffffb3c380138980 EFLAGS: 00010282
>> [12090.273734] RAX: ffff9441c9734458 RBX: ffff9441c9734400 RCX: 0000000000000000
>> [12090.273746] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff9441c9734400
>> [12090.273758] RBP: ffffb3c380138990 R08: 0000000000000000 R09: 0000000000000000
>> [12090.273771] R10: 0000000000000000 R11: 0000000000000000 R12: ffff9441c9734400
>> [12090.273783] R13: 00000000000005dc R14: ffff9441c49dda00 R15: ffffffff9e55ec40
>> [12090.273795] FS:  0000000000000000(0000) GS:ffff9442f7c40000(0000) knlGS:0000000000000000
>> [12090.273811] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> [12090.273823] CR2: ffff9441c9734458 CR3: 0000000155a3a006 CR4: 00000000001706e0
>> [12090.273837] Call Trace:
>> [12090.273845]  <IRQ>
>> [12090.273851]  ? show_regs+0x6d/0x80
>> [12090.273864]  ? __die+0x24/0x80
>> [12090.273873]  ? page_fault_oops+0x99/0x1b0
>> [12090.273884]  ? kernelmode_fixup_or_oops+0xb2/0x140
>> [12090.273896]  ? __bad_area_nosemaphore+0x1a5/0x2c0
>> [12090.273908]  ? bad_area_nosemaphore+0x16/0x30
>> [12090.273918]  ? do_kern_addr_fault+0x7b/0xa0
>> [12090.273927]  ? exc_page_fault+0x1a4/0x1b0
>> [12090.273939]  ? asm_exc_page_fault+0x27/0x30
>> [12090.273952]  ? skb_release_head_state+0x27/0xb0
>> [12090.273964]  consume_skb+0x33/0xf0
>> [12090.273973]  tcp_mtu_probe+0x565/0x5d0
>> [12090.273984]  tcp_write_xmit+0x579/0xab0
>> [12090.273994]  __tcp_push_pending_frames+0x37/0x110
>> [12090.274005]  tcp_rcv_established+0x264/0x730
>> [12090.274015]  ? security_sock_rcv_skb+0x39/0x60
>> [12090.274027]  tcp_v4_do_rcv+0x169/0x2a0
>> [12090.274037]  tcp_v4_rcv+0xd92/0xe00
>> [12090.274046]  ? raw_v4_input+0xaa/0x240
>> [12090.274056]  ip_protocol_deliver_rcu+0x3c/0x210
>> [12090.274068]  ip_local_deliver_finish+0x77/0xa0
>> [12090.274078]  ip_local_deliver+0x6e/0x120
>> [12090.274089]  ? __pfx_ip_local_deliver_finish+0x10/0x10
>> [12090.274369]  ip_sublist_rcv_finish+0x6f/0x80
>> [12090.274638]  ip_sublist_rcv+0x171/0x220
>> [12090.274931]  ? __pfx_ip_rcv_finish+0x10/0x10
>> [12090.275201]  ip_list_rcv+0x102/0x140
>> [12090.275459]  __netif_receive_skb_list_core+0x22d/0x250
>> [12090.275714]  netif_receive_skb_list_internal+0x1a3/0x2d0
>> [12090.275967]  napi_complete_done+0x74/0x1c0
>> [12090.276218]  bnx2_poll_msix+0xa1/0xe0 [bnx2]
>> [12090.276468]  __napi_poll+0x33/0x1f0
>> [12090.276708]  net_rx_action+0x181/0x2e0
>> [12090.276943]  __do_softirq+0xd9/0x346
>> [12090.277172]  ? handle_irq_event+0x52/0x80
>> [12090.277393]  ? handle_edge_irq+0xda/0x250
>> [12090.277604]  __irq_exit_rcu+0x75/0xa0
>> [12090.277812]  irq_exit_rcu+0xe/0x20
>> [12090.278015]  common_interrupt+0xa4/0xb0
>> [12090.278217]  </IRQ>
>> [12090.278411]  <TASK>
>> [12090.278602]  asm_common_interrupt+0x27/0x40
>> [12090.278798] RIP: 0010:cpuidle_enter_state+0xda/0x730
>> [12090.278992] Code: 11 04 ff e8 a8 f5 ff ff 8b 53 04 49 89 c7 0f 1f 44 00 00 31 ff e8 26 bb 02 ff 80 7d d0 00 0f 85 61 02 00 00 fb 0f 1f 44 00 00 <45> 85 f6 0f 88 f7 01 00 00 4d 63 ee 49 83 fd 0a 0f 83 17 05 00 00
>> [12090.279402] RSP: 0018:ffffb3c3800cbe18 EFLAGS: 00000246
>> [12090.279612] RAX: 0000000000000000 RBX: ffff9442f7c7ec00 RCX: 0000000000000000
>> [12090.279827] RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000000
>> [12090.280042] RBP: ffffb3c3800cbe68 R08: 0000000000000000 R09: 0000000000000000
>> [12090.280259] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff9d0d24a0
>> [12090.280478] R13: 0000000000000003 R14: 0000000000000003 R15: 00000afefc75867b
>> [12090.280698]  ? cpuidle_enter_state+0xca/0x730
>> [12090.280918]  ? finish_task_switch.isra.0+0x89/0x2b0
>> [12090.281142]  cpuidle_enter+0x2e/0x50
>> [12090.281363]  call_cpuidle+0x23/0x60
>> [12090.281583]  cpuidle_idle_call+0x11d/0x190
>> [12090.281804]  do_idle+0x82/0xf0
>> [12090.282022]  cpu_startup_entry+0x1d/0x20
>> [12090.282240]  start_secondary+0x129/0x160
>> [12090.282460]  secondary_startup_64_no_verify+0x17e/0x18b
>> [12090.282685]  </TASK>
>> [12090.282902] Modules linked in: tcp_diag inet_diag ip6table_filter ip6_tables xt_LOG nf_log_syslog xt_recent xt_limit xt_tcpudp xt_conntrack iptable_filter xt_CT xt_set iptable_raw bpfilter ip_set_hash_ip ip_set_hash_net ip_set_hash_ipport ip_set_list_set ip_set_bitmap_port ip_set_hash_netiface ip_set nfnetlink binfmt_misc intel_rapl_msr intel_rapl_common x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul polyval_clmulni polyval_generic ghash_clmulni_intel aesni_intel crypto_simd cryptd rapl intel_cstate ipmi_ssif mgag200 drm_shmem_helper cfg80211 input_leds drm_kms_helper dcdbas at24 i2c_i801 lpc_ich i2c_smbus ie31200_edac acpi_ipmi i2c_algo_bit ipmi_si ipmi_devintf ipmi_msghandler sch_fq tcp_bbr nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 libcrc32c drm efi_pstore dmi_sysfs ip_tables x_tables autofs4 hid_generic usbhid hid crc32_pclmul ahci mpt3sas libahci raid_class bnx2 scsi_transport_sas wmi
>> [12090.285082] CR2: ffff9441c9734458
>> ----
> 

Please see [1] for how to decode stack trace symbols.
And also, the most important thing to get this regression fixed
is to find culprit commit by bisecting (for reference see
Documentation/admin-guide/bug-bisect.rst).

[1]: https://lore.kernel.org/all/CANn89iL9Twf+Rzm9v_dwsH_iG4YkW3fAc2Hnx2jypN_Qf9oojw@xxxxxxxxxxxxxx/

Thanks.

-- 
An old man doll... just what I always wanted! - Clara