{ "id": "CVE-2021-47637", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2025-02-26T06:37:05.477", "lastModified": "2025-03-18T19:30:11.170", "vulnStatus": "Analyzed", "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) <-- 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 'out_release' 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) <-- \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 'out_release' 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" } ], "metrics": { "cvssMetricV31": [ { "source": "nvd@nist.gov", "type": "Primary", "cvssData": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH" }, "exploitabilityScore": 1.8, "impactScore": 3.6 } ] }, "weaknesses": [ { "source": "nvd@nist.gov", "type": "Primary", "description": [ { "lang": "en", "value": "CWE-667" } ] } ], "configurations": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.9", "versionEndExcluding": "4.19.238", "matchCriteriaId": "4F595F79-E987-432C-B888-4E73F3873ECD" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "5.4.189", "matchCriteriaId": "8CB6E8F5-C2B1-46F3-A807-0F6104AC340F" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.5", "versionEndExcluding": "5.10.110", "matchCriteriaId": "91D3BFD0-D3F3-4018-957C-96CCBF357D79" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "5.15.33", "matchCriteriaId": "27C42AE8-B387-43E2-938A-E1C8B40BE6D5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "5.16.19", "matchCriteriaId": "20C43679-0439-405A-B97F-685BEE50613B" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.17", "versionEndExcluding": "5.17.2", "matchCriteriaId": "210C679C-CF84-44A3-8939-E629C87E54BF" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/37bdf1ad592555ecda1d55b89f6e393e4c0589d1", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [ "Patch" ] }, { "url": "https://git.kernel.org/stable/c/70e9090acc32348cedc5def0cd6d5c126efc97b9", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [ "Patch" ] }, { "url": "https://git.kernel.org/stable/c/83e42a78428fc354f5e2049935b84c8d8d29b787", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [ "Patch" ] }, { "url": "https://git.kernel.org/stable/c/8b278c8dcfb565cb65eceb62a38cbf7a7c326db5", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [ "Patch" ] }, { "url": "https://git.kernel.org/stable/c/9dddc8211430fb851ddf0b168e3a00c6f66cc185", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [ "Patch" ] }, { "url": "https://git.kernel.org/stable/c/afd427048047e8efdedab30e8888044e2be5aa9c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [ "Patch" ] }, { "url": "https://git.kernel.org/stable/c/c58af8564a7b08757173009030b74baf4b2b762b", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [ "Patch" ] } ] }