The null-dereference crash occurs in cap_capable()

Solution Unverified - Updated -

Issue

  • The null-dereference crash occurs in cap_capable()
[ 4326.818426] BUG: unable to handle kernel NULL pointer dereference at 00000000000000c8
[ 4326.826278] IP: [<ffffffffb6705f49>] cap_capable+0x29/0x80
[ 4326.831787] PGD 800000c5edfb0067 PUD c60ab9d067 PMD 0 
[ 4326.836992] Oops: 0000 [#1] SMP 
[ 4326.840268] Modules linked in: vfat fat mpt3sas mpt2sas raid_class scsi_transport_sas mptctl mptbase nfsv3 nfs_acl nfs lockd grace fscache dell_rbu ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 xt_addrtype iptable_filter xt_conntrack nf_nat nf_conntrack br_netfilter bridge 8021q garp mrp stp llc bonding falcon_lsm_serviceable(PE) falcon_nf_netcontain(PE) falcon_lsm_pinned_10803(E) sunrpc dm_thin_pool dm_persistent_data dm_bio_prison dm_bufio ext4 mbcache jbd2 dell_smbios iTCO_wdt iTCO_vendor_support dell_wmi_descriptor dcdbas intel_powerclamp coretemp intel_rapl iosf_mbi kvm_intel kvm irqbypass crc32_pclmul ghash_clmulni_intel aesni_intel lrw gf128mul glue_helper ablk_helper cryptd pcspkr sg i2c_i801 lpc_ich mei_me mei wmi ipmi_si ipmi_devintf ipmi_msghandler
[ 4326.913111]  acpi_power_meter acpi_pad binfmt_misc ip_tables xfs libcrc32c sr_mod cdrom sd_mod crc_t10dif crct10dif_generic uas usb_storage mgag200 drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm crct10dif_pclmul crct10dif_common i40e ahci crc32c_intel drm igb libahci megaraid_sas ptp libata pps_core dca drm_panel_orientation_quirks i2c_algo_bit nfit libnvdimm dm_mirror dm_region_hash dm_log dm_mod
[ 4326.949417] CPU: 7 PID: 7364 Comm: oacore Kdump: loaded Tainted: P            E  ------------   3.10.0-1160.21.1.el7.x86_64 #1
[ 4326.960768] Hardware name: Dell Inc. PowerEdge R640/0HG0J8, BIOS 2.4.8 11/26/2019
[ 4326.968228] task: ffff8e4333fd5280 ti: ffff8e42fc3b0000 task.ti: ffff8e42fc3b0000
[ 4326.975691] RIP: 0010:[<ffffffffb6705f49>]  [<ffffffffb6705f49>] cap_capable+0x29/0x80
[ 4326.983610] RSP: 0018:ffff8e42fc3b3bf8  EFLAGS: 00010203
[ 4326.988909] RAX: 0000000000000000 RBX: ffff8e4333fd5280 RCX: 0000000000000001
[ 4326.996025] RDX: 0000000000000013 RSI: 0000000000000000 RDI: ffff8d83d07d2840
[ 4327.003140] RBP: ffff8e42fc3b3bf8 R08: ffffffffb704e0c0 R09: ffff8d7fbfc07300
[ 4327.010256] R10: ffff8d7fbfc07300 R11: ffffffffb65ddf1d R12: 000000000000000d
[ 4327.017373] R13: ffff8d840db88000 R14: ffff8d840bfcf580 R15: ffffffffb7055280
[ 4327.024488] FS:  00007f0a459b2700(0000) GS:ffff8efa7d4c0000(0000) knlGS:0000000000000000
[ 4327.032555] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 4327.038286] CR2: 00000000000000c8 CR3: 000000c5d2fc6000 CR4: 00000000007607e0
[ 4327.045404] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 4327.052519] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 4327.059635] PKRU: 55555554
[ 4327.062340] Call Trace:
[ 4327.064792]  [<ffffffffb67082fe>] security_capable+0x1e/0x20
[ 4327.070436]  [<ffffffffb64a94e9>] ns_capable+0x29/0x50
[ 4327.075560]  [<ffffffffb670601c>] cap_ptrace_access_check+0x5c/0xb0
[ 4327.081813]  [<ffffffffb672b11c>] yama_ptrace_access_check+0x2c/0x1a0
[ 4327.088236]  [<ffffffffb6708247>] security_ptrace_access_check+0x17/0x40
[ 4327.094919]  [<ffffffffb64aa6f8>] __ptrace_may_access+0xc8/0x150
[ 4327.100911]  [<ffffffffb64aaa4e>] ptrace_may_access+0x2e/0x50
[ 4327.106646]  [<ffffffffb66ce091>] do_task_stat+0x91/0xbb0
[ 4327.112035]  [<ffffffffb65f9b28>] ? __vma_link_rb+0xb8/0xe0
[ 4327.117590]  [<ffffffffb65fabff>] ? vma_set_page_prot+0x2f/0x50
[ 4327.123494]  [<ffffffffb65fc31c>] ? mmap_region+0x20c/0x670
[ 4327.129055]  [<ffffffffb66cf6e4>] proc_tgid_stat+0x14/0x20
[ 4327.134529]  [<ffffffffb66c98b2>] proc_single_show+0x52/0x90
[ 4327.140175]  [<ffffffffb6676680>] seq_read+0x130/0x440
[ 4327.145301]  [<ffffffffb664db3f>] vfs_read+0x9f/0x170
[ 4327.150340]  [<ffffffffb664e9bf>] SyS_read+0x7f/0xf0
[ 4327.155298]  [<ffffffffb6b96226>] tracesys+0xa6/0xcc
[ 4327.160247] Code: 1f 00 0f 1f 44 00 00 55 4c 8b 87 80 00 00 00 48 89 e5 eb 09 66 0f 1f 44 00 00 48 89 c6 4c 39 c6 74 28 48 81 fe c0 e0 04 b7 74 3f <48> 8b 86 c8 00 00 00 4c 39 c0 75 e3 8b 86 d0 00 00 00 39 47 14 
[ 4327.180677] RIP  [<ffffffffb6705f49>] cap_capable+0x29/0x80
[ 4327.186263]  RSP <ffff8e42fc3b3bf8>
[ 4327.189746] CR2: 00000000000000c8
  • The kernel stack backtrace of the panic task:
PID: 7364   TASK: ffff8e4333fd5280  CPU: 7   COMMAND: "appthread"
 #0 [ffff8e42fc3b3880] machine_kexec at ffffffffb64662c4
 #1 [ffff8e42fc3b38e0] __crash_kexec at ffffffffb6522732
 #2 [ffff8e42fc3b39b0] crash_kexec at ffffffffb6522820
 #3 [ffff8e42fc3b39c8] oops_end at ffffffffb6b8d798
 #4 [ffff8e42fc3b39f0] no_context at ffffffffb6475d14
 #5 [ffff8e42fc3b3a40] __bad_area_nosemaphore at ffffffffb6475fe2
 #6 [ffff8e42fc3b3a90] bad_area_nosemaphore at ffffffffb6476104
 #7 [ffff8e42fc3b3aa0] __do_page_fault at ffffffffb6b90750
 #8 [ffff8e42fc3b3b10] do_page_fault at ffffffffb6b90975
 #9 [ffff8e42fc3b3b40] page_fault at ffffffffb6b8c778
    [exception RIP: cap_capable+41]
    RIP: ffffffffb6705f49  RSP: ffff8e42fc3b3bf8  RFLAGS: 00010203
    RAX: 0000000000000000  RBX: ffff8e4333fd5280  RCX: 0000000000000001
    RDX: 0000000000000013  RSI: 0000000000000000  RDI: ffff8d83d07d2840
    RBP: ffff8e42fc3b3bf8   R8: ffffffffb704e0c0   R9: ffff8d7fbfc07300
    R10: ffff8d7fbfc07300  R11: ffffffffb65ddf1d  R12: 000000000000000d
    R13: ffff8d840db88000  R14: ffff8d840bfcf580  R15: ffffffffb7055280
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
#10 [ffff8e42fc3b3c00] security_capable at ffffffffb67082fe
#11 [ffff8e42fc3b3c10] ns_capable at ffffffffb64a94e9
#12 [ffff8e42fc3b3c28] cap_ptrace_access_check at ffffffffb670601c
#13 [ffff8e42fc3b3c40] yama_ptrace_access_check at ffffffffb672b11c
#14 [ffff8e42fc3b3c78] security_ptrace_access_check at ffffffffb6708247
#15 [ffff8e42fc3b3c98] __ptrace_may_access at ffffffffb64aa6f8
#16 [ffff8e42fc3b3cc0] ptrace_may_access at ffffffffb64aaa4e
#17 [ffff8e42fc3b3ce8] do_task_stat at ffffffffb66ce091
#18 [ffff8e42fc3b3e20] proc_tgid_stat at ffffffffb66cf6e4
#19 [ffff8e42fc3b3e30] proc_single_show at ffffffffb66c98b2
#20 [ffff8e42fc3b3e68] seq_read at ffffffffb6676680
#21 [ffff8e42fc3b3ed8] vfs_read at ffffffffb664db3f
#22 [ffff8e42fc3b3f08] sys_read at ffffffffb664e9bf
 ...

Environment

  • Red Hat Enterprise Linux 7.9 (kernel-3.10.0-1160.21.1.el7)
  • Dell PowerEdge R640

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