NULL pointer dereference in kvdo module code

Issue

System crashing and rebooting due to NULL pointer dereference in kvdo module code

        CPUS: 48
        DATE: Thu Jun 20 23:58:56 EDT 2024
      UPTIME: 17:33:42
LOAD AVERAGE: 10.16, 10.50, 10.62
       TASKS: 2366
    NODENAME: HOSTNAME
     RELEASE: 5.14.0-427.22.1.el9_4.x86_64
     VERSION: #1 SMP PREEMPT_DYNAMIC Mon Jun 10 09:23:36 EDT 2024
     MACHINE: x86_64  (2000 Mhz)
      MEMORY: 255.5 GB
       PANIC: "Oops: 0000 [#1] PREEMPT SMP NOPTI" (check log for details)
         PID: 1645
     COMMAND: "kvdo0:hashQ0"
        TASK: ff329c58cac92380  [THREAD_INFO: ff329c58cac92380]
         CPU: 38
       STATE: TASK_RUNNING (PANIC)

crash> mod -t
NAME  TAINTS
kvdo  O

crash> bt
PID: 1645     TASK: ff329c58cac92380  CPU: 38   COMMAND: "kvdo0:hashQ0"
 #0 [ff6df3744ea33bf0] machine_kexec at ffffffffa9e781e7
 #1 [ff6df3744ea33c48] __crash_kexec at ffffffffa9fef73a
 #2 [ff6df3744ea33d08] crash_kexec at ffffffffa9ff09c8
 #3 [ff6df3744ea33d10] oops_end at ffffffffa9e2f9bb
 #4 [ff6df3744ea33d30] page_fault_oops at ffffffffa9e8a5eb
 #5 [ff6df3744ea33d88] exc_page_fault at ffffffffaaa84ab2
 #6 [ff6df3744ea33db0] asm_exc_page_fault at ffffffffaac00bc2
    [exception RIP: finish_querying+202]
    RIP: ffffffffc144783a  RSP: ff6df3744ea33e60  RFLAGS: 00010246
    RAX: 0000000000000000  RBX: ff6df37460a5f9b8  RCX: 0000000000000017
    RDX: ff6df37460a4a150  RSI: 0000000000000004  RDI: ff6df37460dfc9b0
    RBP: ff6df37460dfc9b0   R8: ff6df37460a4a150   R9: ff6df37460a4a150
    R10: 000000000000002b  R11: ff6df37460dddda0  R12: ff6df37460b114a0
    R13: ff6df37460a01148  R14: ff6df37460a5fa50  R15: ff6df37460a011c0
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 #7 [ff6df3744ea33e98] service_work_queue at ffffffffc148db43 [kvdo]
 #8 [ff6df3744ea33f00] work_queue_runner at ffffffffc148dd88 [kvdo]
 #9 [ff6df3744ea33f18] kthread at ffffffffa9f358cd
#10 [ff6df3744ea33f50] ret_from_fork at ffffffffa9e02c69


crash> log -T | tail -n 60
[Thu Jun 20 10:05:51 EDT 2024] perf: interrupt took too long (4999 > 4976), lowering kernel.perf_event_max_sample_rate to 40000
[Thu Jun 20 10:50:19 EDT 2024] kvdo0:reader: Page 35724 invalidated after read
[Thu Jun 20 10:50:19 EDT 2024] kvdo0:reader: Page 35725 invalidated after read
[Thu Jun 20 10:50:25 EDT 2024] kvdo0:reader: Page 35879 invalidated after read
[Thu Jun 20 11:05:27 EDT 2024] kvdo0:reader: Page 69372 invalidated after read
[Thu Jun 20 11:26:02 EDT 2024] perf: interrupt took too long (6268 > 6248), lowering kernel.perf_event_max_sample_rate to 31000
[Thu Jun 20 11:36:46 EDT 2024] kvdo0:reader: Page 48344 invalidated after read
[Thu Jun 20 12:48:37 EDT 2024] kvdo0:reader: Page 48117 invalidated after read
[Thu Jun 20 13:14:57 EDT 2024] kvdo0:reader: Page 25151 invalidated after read
[Thu Jun 20 13:47:29 EDT 2024] kvdo0:reader: Page 5556 invalidated after read
[Thu Jun 20 14:35:21 EDT 2024] perf: interrupt took too long (7848 > 7835), lowering kernel.perf_event_max_sample_rate to 25000
[Thu Jun 20 16:45:36 EDT 2024] kvdo0:reader: Page 17777 invalidated after read
[Thu Jun 20 17:14:34 EDT 2024] kvdo0:reader: Page 63710 invalidated after read
[Thu Jun 20 17:15:29 EDT 2024] kvdo0:reader: Page 65571 invalidated after read
[Thu Jun 20 17:37:54 EDT 2024] kvdo0:reader: Page 29651 invalidated after read
[Thu Jun 20 17:37:54 EDT 2024] kvdo0:reader: Page 29652 invalidated after read
[Thu Jun 20 22:17:04 EDT 2024] kvdo0:reader: Page 12093 invalidated after read
[Thu Jun 20 23:36:43 EDT 2024] kvdo0:reader: Page 53656 invalidated after read
[Thu Jun 20 23:58:55 EDT 2024] BUG: kernel NULL pointer dereference, address: 0000000000000001
[Thu Jun 20 23:58:55 EDT 2024] #PF: supervisor read access in kernel mode
[Thu Jun 20 23:58:55 EDT 2024] #PF: error_code(0x0000) - not-present page
[Thu Jun 20 23:58:55 EDT 2024] PGD 241ab3e067 P4D 2097597067 PUD 2097596067 PMD 0 
[Thu Jun 20 23:58:55 EDT 2024] Oops: 0000 [#1] PREEMPT SMP NOPTI
[Thu Jun 20 23:58:55 EDT 2024] CPU: 38 PID: 1645 Comm: kvdo0:hashQ0 Kdump: loaded Tainted: G           O      -------  ---  5.14.0-427.22.1.el9_4.x86_64 #1
[Thu Jun 20 23:58:55 EDT 2024] Hardware name: Dell Inc. PowerEdge R760xd2/0J3N69, BIOS 2.2.7 05/13/2024
[Thu Jun 20 23:58:55 EDT 2024] RIP: 0010:finish_querying+0xca/0x310 [kvdo]
[Thu Jun 20 23:58:55 EDT 2024] Code: 49 89 44 24 50 0f 85 d4 01 00 00 41 c7 44 24 34 04 00 00 00 48 8b 85 38 02 00 00 48 89 ef be 04 00 00 00 c6 85 90 01 00 00 04 <0f> b6 40 01 48 c7 45 10 40 63 44 c1 88 45 03 48 83 c4 08 5b 5d 41
[Thu Jun 20 23:58:55 EDT 2024] RSP: 0018:ff6df3744ea33e60 EFLAGS: 00010246
[Thu Jun 20 23:58:55 EDT 2024] RAX: 0000000000000000 RBX: ff6df37460a5f9b8 RCX: 0000000000000017
[Thu Jun 20 23:58:55 EDT 2024] RDX: ff6df37460a4a150 RSI: 0000000000000004 RDI: ff6df37460dfc9b0
[Thu Jun 20 23:58:55 EDT 2024] RBP: ff6df37460dfc9b0 R08: ff6df37460a4a150 R09: ff6df37460a4a150
[Thu Jun 20 23:58:55 EDT 2024] R10: 000000000000002b R11: ff6df37460dddda0 R12: ff6df37460b114a0
[Thu Jun 20 23:58:55 EDT 2024] R13: ff6df37460a01148 R14: ff6df37460a5fa50 R15: ff6df37460a011c0
[Thu Jun 20 23:58:55 EDT 2024] FS:  0000000000000000(0000) GS:ff329c77c00c0000(0000) knlGS:0000000000000000
[Thu Jun 20 23:58:55 EDT 2024] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[Thu Jun 20 23:58:55 EDT 2024] CR2: 0000000000000001 CR3: 0000002f8c802002 CR4: 0000000000771ee0
[Thu Jun 20 23:58:55 EDT 2024] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[Thu Jun 20 23:58:55 EDT 2024] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400
[Thu Jun 20 23:58:55 EDT 2024] PKRU: 55555554
[Thu Jun 20 23:58:55 EDT 2024] Call Trace:
[Thu Jun 20 23:58:55 EDT 2024]  <TASK>
[Thu Jun 20 23:58:55 EDT 2024]  ? show_trace_log_lvl+0x1c4/0x2df
[Thu Jun 20 23:58:55 EDT 2024]  ? show_trace_log_lvl+0x1c4/0x2df
[Thu Jun 20 23:58:55 EDT 2024]  ? service_work_queue+0xb3/0x290 [kvdo]
[Thu Jun 20 23:58:55 EDT 2024]  ? __die_body.cold+0x8/0xd
[Thu Jun 20 23:58:55 EDT 2024]  ? page_fault_oops+0x134/0x170
[Thu Jun 20 23:58:55 EDT 2024]  ? exc_page_fault+0x62/0x150
[Thu Jun 20 23:58:55 EDT 2024]  ? asm_exc_page_fault+0x22/0x30
[Thu Jun 20 23:58:55 EDT 2024]  ? finish_querying+0xca/0x310 [kvdo]
[Thu Jun 20 23:58:55 EDT 2024]  service_work_queue+0xb3/0x290 [kvdo]
[Thu Jun 20 23:58:55 EDT 2024]  ? __pfx_autoremove_wake_function+0x10/0x10
[Thu Jun 20 23:58:55 EDT 2024]  ? __pfx_work_queue_runner+0x10/0x10 [kvdo]
[Thu Jun 20 23:58:55 EDT 2024]  work_queue_runner+0x58/0x70 [kvdo]
[Thu Jun 20 23:58:55 EDT 2024]  kthread+0xdd/0x100
[Thu Jun 20 23:58:55 EDT 2024]  ? __pfx_kthread+0x10/0x10
[Thu Jun 20 23:58:55 EDT 2024]  ret_from_fork+0x29/0x50
[Thu Jun 20 23:58:55 EDT 2024]  </TASK>
[Thu Jun 20 23:58:55 EDT 2024] Modules linked in: bonding tls nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 rfkill ip_set nf_tables nfnetlink vfat fat dm_multipath intel_rapl_msr intel_rapl_common intel_uncore_frequency intel_uncore_frequency_common intel_ifs i10nm_edac nfit libnvdimm x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel iTCO_wdt iTCO_vendor_support kvm irqbypass rapl kvdo(O) dm_bufio ipmi_ssif irdma intel_cstate pmt_telemetry intel_sdsi i40e pmt_class mgag200 i2c_algo_bit drm_shmem_helper dcdbas dell_smbios drm_kms_helper ib_uverbs ses enclosure dell_wmi_descriptor wmi_bmof intel_uncore pcspkr isst_if_mbox_pci syscopyarea ib_core acpi_ipmi mei_me isst_if_mmio sysfillrect isst_if_common intel_vsec i2c_i801 sysimgblt mei ipmi_si fb_sys_fops i2c_ismt i2c_smbus ipmi_devintf ipmi_msghandler acpi_power_meter joydev drm fuse xfs libcrc32c sd_mod sg ahci libahci
[Thu Jun 20 23:58:55 EDT 2024]  crct10dif_pclmul ice iaa_crypto crc32_pclmul mpt3sas libata nvme crc32c_intel nvme_core megaraid_sas ghash_clmulni_intel idxd tg3 raid_class scsi_transport_sas gnss idxd_bus nvme_common wmi t10_pi pinctrl_emmitsburg dm_mirror dm_region_hash dm_log dm_mod
[Thu Jun 20 23:58:55 EDT 2024] CR2: 0000000000000001
crash>