FKIE_CVE-2021-47637
Vulnerability from fkie_nvd - Published: 2025-02-26 06:37 - Updated: 2026-06-17 04:18
Severity
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5 (Medium) - CVSS:3.1/
Summary
In the Linux kernel, the following vulnerability has been resolved:
ubifs: Fix deadlock in concurrent rename whiteout and inode writeback
Following hung tasks:
[ 77.028764] task:kworker/u8:4 state:D stack: 0 pid: 132
[ 77.028820] Call Trace:
[ 77.029027] schedule+0x8c/0x1b0
[ 77.029067] mutex_lock+0x50/0x60
[ 77.029074] ubifs_write_inode+0x68/0x1f0 [ubifs]
[ 77.029117] __writeback_single_inode+0x43c/0x570
[ 77.029128] writeback_sb_inodes+0x259/0x740
[ 77.029148] wb_writeback+0x107/0x4d0
[ 77.029163] wb_workfn+0x162/0x7b0
[ 92.390442] task:aa state:D stack: 0 pid: 1506
[ 92.390448] Call Trace:
[ 92.390458] schedule+0x8c/0x1b0
[ 92.390461] wb_wait_for_completion+0x82/0xd0
[ 92.390469] __writeback_inodes_sb_nr+0xb2/0x110
[ 92.390472] writeback_inodes_sb_nr+0x14/0x20
[ 92.390476] ubifs_budget_space+0x705/0xdd0 [ubifs]
[ 92.390503] do_rename.cold+0x7f/0x187 [ubifs]
[ 92.390549] ubifs_rename+0x8b/0x180 [ubifs]
[ 92.390571] vfs_rename+0xdb2/0x1170
[ 92.390580] do_renameat2+0x554/0x770
, are caused by concurrent rename whiteout and inode writeback processes:
rename_whiteout(Thread 1) wb_workfn(Thread2)
ubifs_rename
do_rename
lock_4_inodes (Hold ui_mutex)
ubifs_budget_space
make_free_space
shrink_liability
__writeback_inodes_sb_nr
bdi_split_work_to_wbs (Queue new wb work)
wb_do_writeback(wb work)
__writeback_single_inode
ubifs_write_inode
LOCK(ui_mutex)
↑
wb_wait_for_completion (Wait wb work) <-- deadlock!
Reproducer (Detail program in [Link]):
1. SYS_renameat2("/mp/dir/file", "/mp/dir/whiteout", RENAME_WHITEOUT)
2. Consume out of space before kernel(mdelay) doing budget for whiteout
Fix it by doing whiteout space budget before locking ubifs inodes.
BTW, it also fixes wrong goto tag 'out_release' in whiteout budget
error handling path(It should at least recover dir i_size and unlock
4 ubifs inodes).
References
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * |
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/ubifs/dir.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "9dddc8211430fb851ddf0b168e3a00c6f66cc185",
"status": "affected",
"version": "9e0a1fff8db56eaaebb74b4a3ef65f86811c4798",
"versionType": "git"
},
{
"lessThan": "37bdf1ad592555ecda1d55b89f6e393e4c0589d1",
"status": "affected",
"version": "9e0a1fff8db56eaaebb74b4a3ef65f86811c4798",
"versionType": "git"
},
{
"lessThan": "83e42a78428fc354f5e2049935b84c8d8d29b787",
"status": "affected",
"version": "9e0a1fff8db56eaaebb74b4a3ef65f86811c4798",
"versionType": "git"
},
{
"lessThan": "c58af8564a7b08757173009030b74baf4b2b762b",
"status": "affected",
"version": "9e0a1fff8db56eaaebb74b4a3ef65f86811c4798",
"versionType": "git"
},
{
"lessThan": "70e9090acc32348cedc5def0cd6d5c126efc97b9",
"status": "affected",
"version": "9e0a1fff8db56eaaebb74b4a3ef65f86811c4798",
"versionType": "git"
},
{
"lessThan": "8b278c8dcfb565cb65eceb62a38cbf7a7c326db5",
"status": "affected",
"version": "9e0a1fff8db56eaaebb74b4a3ef65f86811c4798",
"versionType": "git"
},
{
"lessThan": "afd427048047e8efdedab30e8888044e2be5aa9c",
"status": "affected",
"version": "9e0a1fff8db56eaaebb74b4a3ef65f86811c4798",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"fs/ubifs/dir.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.9"
},
{
"lessThan": "4.9",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "4.19.*",
"status": "unaffected",
"version": "4.19.238",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.4.*",
"status": "unaffected",
"version": "5.4.189",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.110",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.33",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.16.*",
"status": "unaffected",
"version": "5.16.19",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.17.*",
"status": "unaffected",
"version": "5.17.2",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "5.18",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"matchCriteriaId": "4F595F79-E987-432C-B888-4E73F3873ECD",
"versionEndExcluding": "4.19.238",
"versionStartIncluding": "4.9",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"matchCriteriaId": "8CB6E8F5-C2B1-46F3-A807-0F6104AC340F",
"versionEndExcluding": "5.4.189",
"versionStartIncluding": "4.20",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"matchCriteriaId": "91D3BFD0-D3F3-4018-957C-96CCBF357D79",
"versionEndExcluding": "5.10.110",
"versionStartIncluding": "5.5",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"matchCriteriaId": "27C42AE8-B387-43E2-938A-E1C8B40BE6D5",
"versionEndExcluding": "5.15.33",
"versionStartIncluding": "5.11",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"matchCriteriaId": "20C43679-0439-405A-B97F-685BEE50613B",
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{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"matchCriteriaId": "210C679C-CF84-44A3-8939-E629C87E54BF",
"versionEndExcluding": "5.17.2",
"versionStartIncluding": "5.17",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nubifs: Fix deadlock in concurrent rename whiteout and inode writeback\n\nFollowing hung tasks:\n[ 77.028764] task:kworker/u8:4 state:D stack: 0 pid: 132\n[ 77.028820] Call Trace:\n[ 77.029027] schedule+0x8c/0x1b0\n[ 77.029067] mutex_lock+0x50/0x60\n[ 77.029074] ubifs_write_inode+0x68/0x1f0 [ubifs]\n[ 77.029117] __writeback_single_inode+0x43c/0x570\n[ 77.029128] writeback_sb_inodes+0x259/0x740\n[ 77.029148] wb_writeback+0x107/0x4d0\n[ 77.029163] wb_workfn+0x162/0x7b0\n\n[ 92.390442] task:aa state:D stack: 0 pid: 1506\n[ 92.390448] Call Trace:\n[ 92.390458] schedule+0x8c/0x1b0\n[ 92.390461] wb_wait_for_completion+0x82/0xd0\n[ 92.390469] __writeback_inodes_sb_nr+0xb2/0x110\n[ 92.390472] writeback_inodes_sb_nr+0x14/0x20\n[ 92.390476] ubifs_budget_space+0x705/0xdd0 [ubifs]\n[ 92.390503] do_rename.cold+0x7f/0x187 [ubifs]\n[ 92.390549] ubifs_rename+0x8b/0x180 [ubifs]\n[ 92.390571] vfs_rename+0xdb2/0x1170\n[ 92.390580] do_renameat2+0x554/0x770\n\n, are caused by concurrent rename whiteout and inode writeback processes:\n\trename_whiteout(Thread 1)\t wb_workfn(Thread2)\nubifs_rename\n do_rename\n lock_4_inodes (Hold ui_mutex)\n ubifs_budget_space\n make_free_space\n shrink_liability\n\t __writeback_inodes_sb_nr\n\t bdi_split_work_to_wbs (Queue new wb work)\n\t\t\t\t\t wb_do_writeback(wb work)\n\t\t\t\t\t\t__writeback_single_inode\n\t\t\t\t\t ubifs_write_inode\n\t\t\t\t\t LOCK(ui_mutex)\n\t\t\t\t\t\t\t \u2191\n\t wb_wait_for_completion (Wait wb work) \u003c-- deadlock!\n\nReproducer (Detail program in [Link]):\n 1. SYS_renameat2(\"/mp/dir/file\", \"/mp/dir/whiteout\", RENAME_WHITEOUT)\n 2. Consume out of space before kernel(mdelay) doing budget for whiteout\n\nFix it by doing whiteout space budget before locking ubifs inodes.\nBTW, it also fixes wrong goto tag \u0027out_release\u0027 in whiteout budget\nerror handling path(It should at least recover dir i_size and unlock\n4 ubifs inodes)."
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad:\n\nubifs: Se corrige interbloqueo en concurrencia de un renombrado con whiteout simult\u00e1neo a la escritura del inodo.\n\nTareas colgadas:\n[ 77.028764] task:kworker/u8:4 state:D stack: 0 pid: 132\n[ 77.028820] Call Trace:\n[ 77.029027] schedule+0x8c/0x1b0\n[ 77.029067] mutex_lock+0x50/0x60\n[ 77.029074] ubifs_write_inode+0x68/0x1f0 [ubifs]\n[ 77.029117] __writeback_single_inode+0x43c/0x570\n[ 77.029128] writeback_sb_inodes+0x259/0x740\n[ 77.029148] wb_writeback+0x107/0x4d0\n[ 77.029163] wb_workfn+0x162/0x7b0\n\n[ 92.390442] task:aa state:D stack: 0 pid: 1506\n[ 92.390448] Call Trace:\n[ 92.390458] schedule+0x8c/0x1b0\n[ 92.390461] wb_wait_for_completion+0x82/0xd0\n[ 92.390469] __writeback_inodes_sb_nr+0xb2/0x110\n[ 92.390472] writeback_inodes_sb_nr+0x14/0x20\n[ 92.390476] ubifs_budget_space+0x705/0xdd0 [ubifs]\n[ 92.390503] do_rename.cold+0x7f/0x187 [ubifs]\n[ 92.390549] ubifs_rename+0x8b/0x180 [ubifs]\n[ 92.390571] vfs_rename+0xdb2/0x1170\n[ 92.390580] do_renameat2+0x554/0x770\n\n, ocasionado por procesos simult\u00e1neos de renombrado con whiteout y escritura del inodo:\n\trename_whiteout(Thread 1)\t wb_workfn(Thread2)\nubifs_rename\n do_rename\n lock_4_inodes (Hold ui_mutex)\n ubifs_budget_space\n make_free_space\n shrink_liability\n\t __writeback_inodes_sb_nr\n\t bdi_split_work_to_wbs (Queue new wb work)\n\t\t\t\t\t wb_do_writeback(wb work)\n\t\t\t\t\t\t__writeback_single_inode\n\t\t\t\t\t ubifs_write_inode\n\t\t\t\t\t LOCK(ui_mutex)\n\t\t\t\t\t\t\t ?\n\t wb_wait_for_completion (Wait wb work) \u0026lt;-- \u00a1interbloqueo!\n\nCaso de prueba:\n 1. SYS_renameat2(\"/mp/dir/file\", \"/mp/dir/whiteout\", RENAME_WHITEOUT)\n 2. Consumir todo el espacio antes de que kernel(mdelay) planifique el whiteout\n\nArreglado calculando el espacio de whiteout antes de bloquear los inodos de ubifs.\n\nTambi\u00e9n soluciona etiqueta la etiqueta goto err\u00f3nea \u0027out_release\u0027 en el flujo de errores\nde la planificaci\u00f3n del whiteout (al menos deber\u00eda recuperar el directorio i_size y desbloquear 4 inodos de ubifs).\n"
}
],
"id": "CVE-2021-47637",
"lastModified": "2026-06-17T04:18:12.670",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 5.5,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 3.6,
"source": "nvd@nist.gov",
"type": "Primary"
},
{
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"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 5.5,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 3.6,
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2021-47637",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2025-10-01T19:50:51.071622Z",
"version": "2.0.3"
}
}
]
},
"published": "2025-02-26T06:37:05.477",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
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],
"url": "https://git.kernel.org/stable/c/37bdf1ad592555ecda1d55b89f6e393e4c0589d1"
},
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],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Modified",
"weaknesses": [
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"description": [
{
"lang": "en",
"value": "CWE-667"
}
],
"source": "nvd@nist.gov",
"type": "Primary"
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"value": "CWE-667"
}
],
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"type": "Secondary"
}
]
}
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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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