CVE-2022-50635 (GCVE-0-2022-50635)

Vulnerability from cvelistv5 – Published: 2025-12-09 00:00 – Updated: 2025-12-09 00:00
VLAI?
Title
powerpc/kprobes: Fix null pointer reference in arch_prepare_kprobe()
Summary
In the Linux kernel, the following vulnerability has been resolved: powerpc/kprobes: Fix null pointer reference in arch_prepare_kprobe() I found a null pointer reference in arch_prepare_kprobe(): # echo 'p cmdline_proc_show' > kprobe_events # echo 'p cmdline_proc_show+16' >> kprobe_events Kernel attempted to read user page (0) - exploit attempt? (uid: 0) BUG: Kernel NULL pointer dereference on read at 0x00000000 Faulting instruction address: 0xc000000000050bfc Oops: Kernel access of bad area, sig: 11 [#1] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA PowerNV Modules linked in: CPU: 0 PID: 122 Comm: sh Not tainted 6.0.0-rc3-00007-gdcf8e5633e2e #10 NIP: c000000000050bfc LR: c000000000050bec CTR: 0000000000005bdc REGS: c0000000348475b0 TRAP: 0300 Not tainted (6.0.0-rc3-00007-gdcf8e5633e2e) MSR: 9000000000009033 <SF,HV,EE,ME,IR,DR,RI,LE> CR: 88002444 XER: 20040006 CFAR: c00000000022d100 DAR: 0000000000000000 DSISR: 40000000 IRQMASK: 0 ... NIP arch_prepare_kprobe+0x10c/0x2d0 LR arch_prepare_kprobe+0xfc/0x2d0 Call Trace: 0xc0000000012f77a0 (unreliable) register_kprobe+0x3c0/0x7a0 __register_trace_kprobe+0x140/0x1a0 __trace_kprobe_create+0x794/0x1040 trace_probe_create+0xc4/0xe0 create_or_delete_trace_kprobe+0x2c/0x80 trace_parse_run_command+0xf0/0x210 probes_write+0x20/0x40 vfs_write+0xfc/0x450 ksys_write+0x84/0x140 system_call_exception+0x17c/0x3a0 system_call_vectored_common+0xe8/0x278 --- interrupt: 3000 at 0x7fffa5682de0 NIP: 00007fffa5682de0 LR: 0000000000000000 CTR: 0000000000000000 REGS: c000000034847e80 TRAP: 3000 Not tainted (6.0.0-rc3-00007-gdcf8e5633e2e) MSR: 900000000280f033 <SF,HV,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE> CR: 44002408 XER: 00000000 The address being probed has some special: cmdline_proc_show: Probe based on ftrace cmdline_proc_show+16: Probe for the next instruction at the ftrace location The ftrace-based kprobe does not generate kprobe::ainsn::insn, it gets set to NULL. In arch_prepare_kprobe() it will check for: ... prev = get_kprobe(p->addr - 1); preempt_enable_no_resched(); if (prev && ppc_inst_prefixed(ppc_inst_read(prev->ainsn.insn))) { ... If prev is based on ftrace, 'ppc_inst_read(prev->ainsn.insn)' will occur with a null pointer reference. At this point prev->addr will not be a prefixed instruction, so the check can be skipped. Check if prev is ftrace-based kprobe before reading 'prev->ainsn.insn' to fix this problem. [mpe: Trim oops]
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: b4657f7650babc9bfb41ce875abe41b18604a105 , < 7f536a8cb62dd5c084f112373fc34cdb5168a813 (git)
Affected: b4657f7650babc9bfb41ce875abe41b18604a105 , < 4eac4f6a86ae73ef4b772d37398beeba2fbfde4e (git)
Affected: b4657f7650babc9bfb41ce875abe41b18604a105 , < 5fd1b369387c53ee6c774ab86e32e362a1e537ac (git)
Affected: b4657f7650babc9bfb41ce875abe41b18604a105 , < 97f88a3d723162781d6cbfdc7b9617eefab55b19 (git)
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    Linux Linux Affected: 5.8
Unaffected: 0 , < 5.8 (semver)
Unaffected: 5.15.75 , ≤ 5.15.* (semver)
Unaffected: 5.19.17 , ≤ 5.19.* (semver)
Unaffected: 6.0.3 , ≤ 6.0.* (semver)
Unaffected: 6.1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/powerpc/kernel/kprobes.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "7f536a8cb62dd5c084f112373fc34cdb5168a813",
              "status": "affected",
              "version": "b4657f7650babc9bfb41ce875abe41b18604a105",
              "versionType": "git"
            },
            {
              "lessThan": "4eac4f6a86ae73ef4b772d37398beeba2fbfde4e",
              "status": "affected",
              "version": "b4657f7650babc9bfb41ce875abe41b18604a105",
              "versionType": "git"
            },
            {
              "lessThan": "5fd1b369387c53ee6c774ab86e32e362a1e537ac",
              "status": "affected",
              "version": "b4657f7650babc9bfb41ce875abe41b18604a105",
              "versionType": "git"
            },
            {
              "lessThan": "97f88a3d723162781d6cbfdc7b9617eefab55b19",
              "status": "affected",
              "version": "b4657f7650babc9bfb41ce875abe41b18604a105",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/powerpc/kernel/kprobes.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.8"
            },
            {
              "lessThan": "5.8",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.75",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.19.*",
              "status": "unaffected",
              "version": "5.19.17",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.0.*",
              "status": "unaffected",
              "version": "6.0.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.75",
                  "versionStartIncluding": "5.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.19.17",
                  "versionStartIncluding": "5.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.0.3",
                  "versionStartIncluding": "5.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1",
                  "versionStartIncluding": "5.8",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/kprobes: Fix null pointer reference in arch_prepare_kprobe()\n\nI found a null pointer reference in arch_prepare_kprobe():\n\n  # echo \u0027p cmdline_proc_show\u0027 \u003e kprobe_events\n  # echo \u0027p cmdline_proc_show+16\u0027 \u003e\u003e kprobe_events\n  Kernel attempted to read user page (0) - exploit attempt? (uid: 0)\n  BUG: Kernel NULL pointer dereference on read at 0x00000000\n  Faulting instruction address: 0xc000000000050bfc\n  Oops: Kernel access of bad area, sig: 11 [#1]\n  LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA PowerNV\n  Modules linked in:\n  CPU: 0 PID: 122 Comm: sh Not tainted 6.0.0-rc3-00007-gdcf8e5633e2e #10\n  NIP:  c000000000050bfc LR: c000000000050bec CTR: 0000000000005bdc\n  REGS: c0000000348475b0 TRAP: 0300   Not tainted  (6.0.0-rc3-00007-gdcf8e5633e2e)\n  MSR:  9000000000009033 \u003cSF,HV,EE,ME,IR,DR,RI,LE\u003e  CR: 88002444  XER: 20040006\n  CFAR: c00000000022d100 DAR: 0000000000000000 DSISR: 40000000 IRQMASK: 0\n  ...\n  NIP arch_prepare_kprobe+0x10c/0x2d0\n  LR  arch_prepare_kprobe+0xfc/0x2d0\n  Call Trace:\n    0xc0000000012f77a0 (unreliable)\n    register_kprobe+0x3c0/0x7a0\n    __register_trace_kprobe+0x140/0x1a0\n    __trace_kprobe_create+0x794/0x1040\n    trace_probe_create+0xc4/0xe0\n    create_or_delete_trace_kprobe+0x2c/0x80\n    trace_parse_run_command+0xf0/0x210\n    probes_write+0x20/0x40\n    vfs_write+0xfc/0x450\n    ksys_write+0x84/0x140\n    system_call_exception+0x17c/0x3a0\n    system_call_vectored_common+0xe8/0x278\n  --- interrupt: 3000 at 0x7fffa5682de0\n  NIP:  00007fffa5682de0 LR: 0000000000000000 CTR: 0000000000000000\n  REGS: c000000034847e80 TRAP: 3000   Not tainted  (6.0.0-rc3-00007-gdcf8e5633e2e)\n  MSR:  900000000280f033 \u003cSF,HV,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE\u003e  CR: 44002408  XER: 00000000\n\nThe address being probed has some special:\n\n  cmdline_proc_show: Probe based on ftrace\n  cmdline_proc_show+16: Probe for the next instruction at the ftrace location\n\nThe ftrace-based kprobe does not generate kprobe::ainsn::insn, it gets\nset to NULL. In arch_prepare_kprobe() it will check for:\n\n  ...\n  prev = get_kprobe(p-\u003eaddr - 1);\n  preempt_enable_no_resched();\n  if (prev \u0026\u0026 ppc_inst_prefixed(ppc_inst_read(prev-\u003eainsn.insn))) {\n  ...\n\nIf prev is based on ftrace, \u0027ppc_inst_read(prev-\u003eainsn.insn)\u0027 will occur\nwith a null pointer reference. At this point prev-\u003eaddr will not be a\nprefixed instruction, so the check can be skipped.\n\nCheck if prev is ftrace-based kprobe before reading \u0027prev-\u003eainsn.insn\u0027\nto fix this problem.\n\n[mpe: Trim oops]"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-12-09T00:00:08.590Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/7f536a8cb62dd5c084f112373fc34cdb5168a813"
        },
        {
          "url": "https://git.kernel.org/stable/c/4eac4f6a86ae73ef4b772d37398beeba2fbfde4e"
        },
        {
          "url": "https://git.kernel.org/stable/c/5fd1b369387c53ee6c774ab86e32e362a1e537ac"
        },
        {
          "url": "https://git.kernel.org/stable/c/97f88a3d723162781d6cbfdc7b9617eefab55b19"
        }
      ],
      "title": "powerpc/kprobes: Fix null pointer reference in arch_prepare_kprobe()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2022-50635",
    "datePublished": "2025-12-09T00:00:08.590Z",
    "dateReserved": "2025-12-08T23:57:43.370Z",
    "dateUpdated": "2025-12-09T00:00:08.590Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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