ghsa-64ww-mp7v-2p59
Vulnerability from github
Published
2025-10-22 18:30
Modified
2025-10-22 18:30
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Details

In the Linux kernel, the following vulnerability has been resolved:

powerpc/rtas: Keep MSR[RI] set when calling RTAS

RTAS runs in real mode (MSR[DR] and MSR[IR] unset) and in 32-bit big endian mode (MSR[SF,LE] unset).

The change in MSR is done in enter_rtas() in a relatively complex way, since the MSR value could be hardcoded.

Furthermore, a panic has been reported when hitting the watchdog interrupt while running in RTAS, this leads to the following stack trace:

watchdog: CPU 24 Hard LOCKUP watchdog: CPU 24 TB:997512652051031, last heartbeat TB:997504470175378 (15980ms ago) ... Supported: No, Unreleased kernel CPU: 24 PID: 87504 Comm: drmgr Kdump: loaded Tainted: G E X 5.14.21-150400.71.1.bz196362_2-default #1 SLE15-SP4 (unreleased) 0d821077ef4faa8dfaf370efb5fdca1fa35f4e2c NIP: 000000001fb41050 LR: 000000001fb4104c CTR: 0000000000000000 REGS: c00000000fc33d60 TRAP: 0100 Tainted: G E X (5.14.21-150400.71.1.bz196362_2-default) MSR: 8000000002981000 CR: 48800002 XER: 20040020 CFAR: 000000000000011c IRQMASK: 1 GPR00: 0000000000000003 ffffffffffffffff 0000000000000001 00000000000050dc GPR04: 000000001ffb6100 0000000000000020 0000000000000001 000000001fb09010 GPR08: 0000000020000000 0000000000000000 0000000000000000 0000000000000000 GPR12: 80040000072a40a8 c00000000ff8b680 0000000000000007 0000000000000034 GPR16: 000000001fbf6e94 000000001fbf6d84 000000001fbd1db0 000000001fb3f008 GPR20: 000000001fb41018 ffffffffffffffff 000000000000017f fffffffffffff68f GPR24: 000000001fb18fe8 000000001fb3e000 000000001fb1adc0 000000001fb1cf40 GPR28: 000000001fb26000 000000001fb460f0 000000001fb17f18 000000001fb17000 NIP [000000001fb41050] 0x1fb41050 LR [000000001fb4104c] 0x1fb4104c Call Trace: Instruction dump: XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX Oops: Unrecoverable System Reset, sig: 6 [#1] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries ... Supported: No, Unreleased kernel CPU: 24 PID: 87504 Comm: drmgr Kdump: loaded Tainted: G E X 5.14.21-150400.71.1.bz196362_2-default #1 SLE15-SP4 (unreleased) 0d821077ef4faa8dfaf370efb5fdca1fa35f4e2c NIP: 000000001fb41050 LR: 000000001fb4104c CTR: 0000000000000000 REGS: c00000000fc33d60 TRAP: 0100 Tainted: G E X (5.14.21-150400.71.1.bz196362_2-default) MSR: 8000000002981000 CR: 48800002 XER: 20040020 CFAR: 000000000000011c IRQMASK: 1 GPR00: 0000000000000003 ffffffffffffffff 0000000000000001 00000000000050dc GPR04: 000000001ffb6100 0000000000000020 0000000000000001 000000001fb09010 GPR08: 0000000020000000 0000000000000000 0000000000000000 0000000000000000 GPR12: 80040000072a40a8 c00000000ff8b680 0000000000000007 0000000000000034 GPR16: 000000001fbf6e94 000000001fbf6d84 000000001fbd1db0 000000001fb3f008 GPR20: 000000001fb41018 ffffffffffffffff 000000000000017f fffffffffffff68f GPR24: 000000001fb18fe8 000000001fb3e000 000000001fb1adc0 000000001fb1cf40 GPR28: 000000001fb26000 000000001fb460f0 000000001fb17f18 000000001fb17000 NIP [000000001fb41050] 0x1fb41050 LR [000000001fb4104c] 0x1fb4104c Call Trace: Instruction dump: XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX ---[ end trace 3ddec07f638c34a2 ]---

This happens because MSR[RI] is unset when entering RTAS but there is no valid reason to not set it here.

RTAS is expected to be called with MSR[RI] as specified in PAPR+ section "7.2.1 Machine State":

R1–7.2.1–9. If called with MSR[RI] equal to 1, then RTAS must protect its own critical regions from recursion by setting the MSR[RI] bit to 0 when in the critical regions.

Fixing this by reviewing the way MSR is compute before calling RTAS. Now a hardcoded value meaning real ---truncated---

Show details on source website

To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2022-49440"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-02-26T07:01:20Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/rtas: Keep MSR[RI] set when calling RTAS\n\nRTAS runs in real mode (MSR[DR] and MSR[IR] unset) and in 32-bit big\nendian mode (MSR[SF,LE] unset).\n\nThe change in MSR is done in enter_rtas() in a relatively complex way,\nsince the MSR value could be hardcoded.\n\nFurthermore, a panic has been reported when hitting the watchdog interrupt\nwhile running in RTAS, this leads to the following stack trace:\n\n  watchdog: CPU 24 Hard LOCKUP\n  watchdog: CPU 24 TB:997512652051031, last heartbeat TB:997504470175378 (15980ms ago)\n  ...\n  Supported: No, Unreleased kernel\n  CPU: 24 PID: 87504 Comm: drmgr Kdump: loaded Tainted: G            E  X    5.14.21-150400.71.1.bz196362_2-default #1 SLE15-SP4 (unreleased) 0d821077ef4faa8dfaf370efb5fdca1fa35f4e2c\n  NIP:  000000001fb41050 LR: 000000001fb4104c CTR: 0000000000000000\n  REGS: c00000000fc33d60 TRAP: 0100   Tainted: G            E  X     (5.14.21-150400.71.1.bz196362_2-default)\n  MSR:  8000000002981000 \u003cSF,VEC,VSX,ME\u003e  CR: 48800002  XER: 20040020\n  CFAR: 000000000000011c IRQMASK: 1\n  GPR00: 0000000000000003 ffffffffffffffff 0000000000000001 00000000000050dc\n  GPR04: 000000001ffb6100 0000000000000020 0000000000000001 000000001fb09010\n  GPR08: 0000000020000000 0000000000000000 0000000000000000 0000000000000000\n  GPR12: 80040000072a40a8 c00000000ff8b680 0000000000000007 0000000000000034\n  GPR16: 000000001fbf6e94 000000001fbf6d84 000000001fbd1db0 000000001fb3f008\n  GPR20: 000000001fb41018 ffffffffffffffff 000000000000017f fffffffffffff68f\n  GPR24: 000000001fb18fe8 000000001fb3e000 000000001fb1adc0 000000001fb1cf40\n  GPR28: 000000001fb26000 000000001fb460f0 000000001fb17f18 000000001fb17000\n  NIP [000000001fb41050] 0x1fb41050\n  LR [000000001fb4104c] 0x1fb4104c\n  Call Trace:\n  Instruction dump:\n  XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX\n  XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX\n  Oops: Unrecoverable System Reset, sig: 6 [#1]\n  LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries\n  ...\n  Supported: No, Unreleased kernel\n  CPU: 24 PID: 87504 Comm: drmgr Kdump: loaded Tainted: G            E  X    5.14.21-150400.71.1.bz196362_2-default #1 SLE15-SP4 (unreleased) 0d821077ef4faa8dfaf370efb5fdca1fa35f4e2c\n  NIP:  000000001fb41050 LR: 000000001fb4104c CTR: 0000000000000000\n  REGS: c00000000fc33d60 TRAP: 0100   Tainted: G            E  X     (5.14.21-150400.71.1.bz196362_2-default)\n  MSR:  8000000002981000 \u003cSF,VEC,VSX,ME\u003e  CR: 48800002  XER: 20040020\n  CFAR: 000000000000011c IRQMASK: 1\n  GPR00: 0000000000000003 ffffffffffffffff 0000000000000001 00000000000050dc\n  GPR04: 000000001ffb6100 0000000000000020 0000000000000001 000000001fb09010\n  GPR08: 0000000020000000 0000000000000000 0000000000000000 0000000000000000\n  GPR12: 80040000072a40a8 c00000000ff8b680 0000000000000007 0000000000000034\n  GPR16: 000000001fbf6e94 000000001fbf6d84 000000001fbd1db0 000000001fb3f008\n  GPR20: 000000001fb41018 ffffffffffffffff 000000000000017f fffffffffffff68f\n  GPR24: 000000001fb18fe8 000000001fb3e000 000000001fb1adc0 000000001fb1cf40\n  GPR28: 000000001fb26000 000000001fb460f0 000000001fb17f18 000000001fb17000\n  NIP [000000001fb41050] 0x1fb41050\n  LR [000000001fb4104c] 0x1fb4104c\n  Call Trace:\n  Instruction dump:\n  XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX\n  XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX\n  ---[ end trace 3ddec07f638c34a2 ]---\n\nThis happens because MSR[RI] is unset when entering RTAS but there is no\nvalid reason to not set it here.\n\nRTAS is expected to be called with MSR[RI] as specified in PAPR+ section\n\"7.2.1 Machine State\":\n\n  R1\u20137.2.1\u20139. If called with MSR[RI] equal to 1, then RTAS must protect\n  its own critical regions from recursion by setting the MSR[RI] bit to\n  0 when in the critical regions.\n\nFixing this by reviewing the way MSR is compute before calling RTAS. Now a\nhardcoded value meaning real \n---truncated---",
  "id": "GHSA-64ww-mp7v-2p59",
  "modified": "2025-10-22T18:30:31Z",
  "published": "2025-10-22T18:30:31Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-49440"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5ca40fcf0da0ce2b5bc44e7d8b036535955f2e3d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5f4367448f6817c8a0e94dc9736ed84fa8eee4a3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b6b1c3ce06ca438eb24e0f45bf0e63ecad0369f5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c9c41f0273826a13ac93124e66a4ff45df281ba0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}


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