CVE-2026-46250 (GCVE-0-2026-46250)
Vulnerability from cvelistv5
Published
2026-06-03 15:49
Modified
2026-08-05 12:30
Severity ?
7.3 (High) - CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: MIPS: Work around LLVM bug when gp is used as global register variable On MIPS, __current_thread_info is defined as global register variable locating in $gp, and is simply assigned with new address during kernel relocation. This however is broken with LLVM, which always restores $gp if it finds $gp is clobbered in any form, including when intentionally through a global register variable. This is against GCC's documentation[1], which requires a callee-saved register used as global register variable not to be restored if it's clobbered. As a result, $gp will continue to point to the unrelocated kernel after the epilog of relocate_kernel(), leading to an early crash in init_idle, [ 0.000000] CPU 0 Unable to handle kernel paging request at virtual address 0000000000000000, epc == ffffffff81afada8, ra == ffffffff81afad90 [ 0.000000] Oops[#1]: [ 0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper Tainted: G W 6.19.0-rc5-00262-gd3eeb99bbc99-dirty #188 VOLUNTARY [ 0.000000] Tainted: [W]=WARN [ 0.000000] Hardware name: loongson,loongson64v-4core-virtio [ 0.000000] $ 0 : 0000000000000000 0000000000000000 0000000000000001 0000000000000000 [ 0.000000] $ 4 : ffffffff80b80ec0 ffffffff80b53d48 0000000000000000 00000000000f4240 [ 0.000000] $ 8 : 0000000000000100 ffffffff81d82f80 ffffffff81d82f80 0000000000000001 [ 0.000000] $12 : 0000000000000000 ffffffff81776f58 00000000000005da 0000000000000002 [ 0.000000] $16 : ffffffff80b80e40 0000000000000000 ffffffff80b81614 9800000005dfbe80 [ 0.000000] $20 : 00000000540000e0 ffffffff81980000 0000000000000000 ffffffff80f81c80 [ 0.000000] $24 : 0000000000000a26 ffffffff8114fb90 [ 0.000000] $28 : ffffffff80b50000 ffffffff80b53d40 0000000000000000 ffffffff81afad90 [ 0.000000] Hi : 0000000000000000 [ 0.000000] Lo : 0000000000000000 [ 0.000000] epc : ffffffff81afada8 init_idle+0x130/0x270 [ 0.000000] ra : ffffffff81afad90 init_idle+0x118/0x270 [ 0.000000] Status: 540000e2 KX SX UX KERNEL EXL [ 0.000000] Cause : 00000008 (ExcCode 02) [ 0.000000] BadVA : 0000000000000000 [ 0.000000] PrId : 00006305 (ICT Loongson-3) [ 0.000000] Process swapper (pid: 0, threadinfo=(____ptrval____), task=(____ptrval____), tls=0000000000000000) [ 0.000000] Stack : 9800000005dfbf00 ffffffff8178e950 0000000000000000 0000000000000000 [ 0.000000] 0000000000000000 ffffffff81970000 000000000000003f ffffffff810a6528 [ 0.000000] 0000000000000001 9800000005dfbe80 9800000005dfbf00 ffffffff81980000 [ 0.000000] ffffffff810a6450 ffffffff81afb6c0 0000000000000000 ffffffff810a2258 [ 0.000000] ffffffff81d82ec8 ffffffff8198d010 ffffffff81b67e80 ffffffff8197dd98 [ 0.000000] ffffffff81d81c80 ffffffff81930000 0000000000000040 0000000000000000 [ 0.000000] 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 0.000000] 0000000000000000 000000000000009e ffffffff9fc01000 0000000000000000 [ 0.000000] 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 0.000000] 0000000000000000 ffffffff81ae86dc ffffffff81b3c741 0000000000000002 [ 0.000000] ... [ 0.000000] Call Trace: [ 0.000000] [<ffffffff81afada8>] init_idle+0x130/0x270 [ 0.000000] [<ffffffff81afb6c0>] sched_init+0x5c8/0x6c0 [ 0.000000] [<ffffffff81ae86dc>] start_kernel+0x27c/0x7a8 This bug has been reported to LLVM[2] and affects version from (at least) 18 to 21. Let's work around this by using inline assembly to assign $gp before a fix is widely available.
References
Impacted products
Vendor Product Version
Linux Linux Version: 279b991b24d2439fbe9d2f093988b9c8aed2603d
Version: 279b991b24d2439fbe9d2f093988b9c8aed2603d
Version: 279b991b24d2439fbe9d2f093988b9c8aed2603d
Version: 279b991b24d2439fbe9d2f093988b9c8aed2603d
Version: 279b991b24d2439fbe9d2f093988b9c8aed2603d
Version: 279b991b24d2439fbe9d2f093988b9c8aed2603d
Version: 279b991b24d2439fbe9d2f093988b9c8aed2603d
Version: 279b991b24d2439fbe9d2f093988b9c8aed2603d
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/mips/kernel/relocate.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "279b991b24d2439fbe9d2f093988b9c8aed2603d",
              "versionType": "git"
            },
            {
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              "status": "affected",
              "version": "279b991b24d2439fbe9d2f093988b9c8aed2603d",
              "versionType": "git"
            },
            {
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              "status": "affected",
              "version": "279b991b24d2439fbe9d2f093988b9c8aed2603d",
              "versionType": "git"
            },
            {
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              "status": "affected",
              "version": "279b991b24d2439fbe9d2f093988b9c8aed2603d",
              "versionType": "git"
            },
            {
              "lessThan": "e3a6498a63394218561065a9a7a597a204f52f6a",
              "status": "affected",
              "version": "279b991b24d2439fbe9d2f093988b9c8aed2603d",
              "versionType": "git"
            },
            {
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              "status": "affected",
              "version": "279b991b24d2439fbe9d2f093988b9c8aed2603d",
              "versionType": "git"
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            {
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              "status": "affected",
              "version": "279b991b24d2439fbe9d2f093988b9c8aed2603d",
              "versionType": "git"
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            {
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              "status": "affected",
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              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/mips/kernel/relocate.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.7"
            },
            {
              "lessThan": "4.7",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.252",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.202",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.165",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.128",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.75",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.14",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.252",
                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.202",
                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.165",
                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.128",
                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.75",
                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.14",
                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.4",
                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nMIPS: Work around LLVM bug when gp is used as global register variable\n\nOn MIPS, __current_thread_info is defined as global register variable\nlocating in $gp, and is simply assigned with new address during kernel\nrelocation.\n\nThis however is broken with LLVM, which always restores $gp if it finds\n$gp is clobbered in any form, including when intentionally through a\nglobal register variable. This is against GCC\u0027s documentation[1], which\nrequires a callee-saved register used as global register variable not to\nbe restored if it\u0027s clobbered.\n\nAs a result, $gp will continue to point to the unrelocated kernel after\nthe epilog of relocate_kernel(), leading to an early crash in init_idle,\n\n[    0.000000] CPU 0 Unable to handle kernel paging request at virtual address 0000000000000000, epc == ffffffff81afada8, ra == ffffffff81afad90\n[    0.000000] Oops[#1]:\n[    0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper Tainted: G        W           6.19.0-rc5-00262-gd3eeb99bbc99-dirty #188 VOLUNTARY\n[    0.000000] Tainted: [W]=WARN\n[    0.000000] Hardware name: loongson,loongson64v-4core-virtio\n[    0.000000] $ 0   : 0000000000000000 0000000000000000 0000000000000001 0000000000000000\n[    0.000000] $ 4   : ffffffff80b80ec0 ffffffff80b53d48 0000000000000000 00000000000f4240\n[    0.000000] $ 8   : 0000000000000100 ffffffff81d82f80 ffffffff81d82f80 0000000000000001\n[    0.000000] $12   : 0000000000000000 ffffffff81776f58 00000000000005da 0000000000000002\n[    0.000000] $16   : ffffffff80b80e40 0000000000000000 ffffffff80b81614 9800000005dfbe80\n[    0.000000] $20   : 00000000540000e0 ffffffff81980000 0000000000000000 ffffffff80f81c80\n[    0.000000] $24   : 0000000000000a26 ffffffff8114fb90\n[    0.000000] $28   : ffffffff80b50000 ffffffff80b53d40 0000000000000000 ffffffff81afad90\n[    0.000000] Hi    : 0000000000000000\n[    0.000000] Lo    : 0000000000000000\n[    0.000000] epc   : ffffffff81afada8 init_idle+0x130/0x270\n[    0.000000] ra    : ffffffff81afad90 init_idle+0x118/0x270\n[    0.000000] Status: 540000e2\tKX SX UX KERNEL EXL\n[    0.000000] Cause : 00000008 (ExcCode 02)\n[    0.000000] BadVA : 0000000000000000\n[    0.000000] PrId  : 00006305 (ICT Loongson-3)\n[    0.000000] Process swapper (pid: 0, threadinfo=(____ptrval____), task=(____ptrval____), tls=0000000000000000)\n[    0.000000] Stack : 9800000005dfbf00 ffffffff8178e950 0000000000000000 0000000000000000\n[    0.000000]         0000000000000000 ffffffff81970000 000000000000003f ffffffff810a6528\n[    0.000000]         0000000000000001 9800000005dfbe80 9800000005dfbf00 ffffffff81980000\n[    0.000000]         ffffffff810a6450 ffffffff81afb6c0 0000000000000000 ffffffff810a2258\n[    0.000000]         ffffffff81d82ec8 ffffffff8198d010 ffffffff81b67e80 ffffffff8197dd98\n[    0.000000]         ffffffff81d81c80 ffffffff81930000 0000000000000040 0000000000000000\n[    0.000000]         0000000000000000 0000000000000000 0000000000000000 0000000000000000\n[    0.000000]         0000000000000000 000000000000009e ffffffff9fc01000 0000000000000000\n[    0.000000]         0000000000000000 0000000000000000 0000000000000000 0000000000000000\n[    0.000000]         0000000000000000 ffffffff81ae86dc ffffffff81b3c741 0000000000000002\n[    0.000000]         ...\n[    0.000000] Call Trace:\n[    0.000000] [\u003cffffffff81afada8\u003e] init_idle+0x130/0x270\n[    0.000000] [\u003cffffffff81afb6c0\u003e] sched_init+0x5c8/0x6c0\n[    0.000000] [\u003cffffffff81ae86dc\u003e] start_kernel+0x27c/0x7a8\n\nThis bug has been reported to LLVM[2] and affects version from (at\nleast) 18 to 21. Let\u0027s work around this by using inline assembly to\nassign $gp before a fix is widely available."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.3,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The vulnerable code runs only during early boot in `relocate_kernel()` (`arch/mips/kernel/head.S` \u2192 `arch/mips/kernel/relocate.c`), before any network stack or syscall interface exists; the only way to reach it is to boot or reboot the MIPS system locally.\nAC:L - When the kernel is built with LLVM/Clang, `CONFIG_RELOCATABLE`, and KASLR relocation (`offset != 0`), LLVM deterministically restores `$gp` in the `relocate_kernel()` epilog, causing a reliable crash in `init_idle()` on every affected boot without races or attacker-uncontrollable timing.\nPR:N - Execution occurs in the pre-authentication boot path (PID 0 swapper during `start_kernel()` \u2192 `sched_init()` \u2192 `init_idle()`), before any user login or privilege checks; no attacker credentials are required at the time the bug triggers.\nUI:N - No victim user action is required beyond normal system power-on or reboot; the fault occurs automatically during kernel initialization on affected builds.\nS:U - Impact is confined to kernel boot failure on the same machine; there is no crossing of security boundaries such as VM escape, sandbox escape, or IOMMU bypass.\nC:L - The stale `$gp`/`__current_thread_info` causes `current` to resolve from the unrelocated `init_thread_union`, leading to dereferences of invalid kernel memory and limited kernel-address information exposure in the oops before the paging fault at address 0.\nI:L - Before the fatal fault, `init_idle()` performs writes through the mis-resolved `current` pointer (e.g., task state and scheduler fields), enabling limited unintended modification of kernel structures even though the immediate outcome is a crash rather than controlled code execution.\nA:H - The bug produces a kernel oops during early boot in `init_idle()` with \"Unable to handle kernel paging request at virtual address 0000000000000000\", preventing the system from completing initialization and rendering it unavailable."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:30:44.867Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/05bff9b0ae095b2420cfebb4a96759a09334bec6"
        },
        {
          "url": "https://git.kernel.org/stable/c/1fe3b402b1e97a1718df3be0a1d3eee20133e735"
        },
        {
          "url": "https://git.kernel.org/stable/c/4dc65b40fb80c2020efbf139b9a38d30f9a37b92"
        },
        {
          "url": "https://git.kernel.org/stable/c/c0155dee51b9f5f48aaf5c71cae005eb0e36521f"
        },
        {
          "url": "https://git.kernel.org/stable/c/e3a6498a63394218561065a9a7a597a204f52f6a"
        },
        {
          "url": "https://git.kernel.org/stable/c/561834f6d6f52b8a1791331e94b2aac753491d2a"
        },
        {
          "url": "https://git.kernel.org/stable/c/9bc3b0ae5203aba650297fdf3e1e774125e423f2"
        },
        {
          "url": "https://git.kernel.org/stable/c/30bfc2d6a1132a89a5f1c3b96c59cf3e4d076ea3"
        }
      ],
      "title": "MIPS: Work around LLVM bug when gp is used as global register variable",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-46250",
    "datePublished": "2026-06-03T15:49:46.390Z",
    "dateReserved": "2026-05-13T15:03:33.107Z",
    "dateUpdated": "2026-08-05T12:30:44.867Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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