{"id":"CVE-2021-47637","state":"PUBLISHED","title":"ubifs: Fix deadlock in concurrent rename whiteout and inode writeback","description":"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   ↑\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).","publishedAt":"2025-02-26T01:54:10.709Z","updatedAt":"2026-05-11T13:58:14.868Z","severity":{"score":5.5,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","source":"CISA-ADP"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"9e0a1fff8db56eaaebb74b4a3ef65f86811c4798","status":"affected","lessThan":"9dddc8211430fb851ddf0b168e3a00c6f66cc185","versionType":"git"},{"version":"9e0a1fff8db56eaaebb74b4a3ef65f86811c4798","status":"affected","lessThan":"37bdf1ad592555ecda1d55b89f6e393e4c0589d1","versionType":"git"},{"version":"9e0a1fff8db56eaaebb74b4a3ef65f86811c4798","status":"affected","lessThan":"83e42a78428fc354f5e2049935b84c8d8d29b787","versionType":"git"},{"version":"9e0a1fff8db56eaaebb74b4a3ef65f86811c4798","status":"affected","lessThan":"c58af8564a7b08757173009030b74baf4b2b762b","versionType":"git"},{"version":"9e0a1fff8db56eaaebb74b4a3ef65f86811c4798","status":"affected","lessThan":"70e9090acc32348cedc5def0cd6d5c126efc97b9","versionType":"git"},{"version":"9e0a1fff8db56eaaebb74b4a3ef65f86811c4798","status":"affected","lessThan":"8b278c8dcfb565cb65eceb62a38cbf7a7c326db5","versionType":"git"},{"version":"9e0a1fff8db56eaaebb74b4a3ef65f86811c4798","status":"affected","lessThan":"afd427048047e8efdedab30e8888044e2be5aa9c","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ubifs/dir.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.9","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.9","versionType":"semver"},{"version":"4.19.238","status":"unaffected","lessThanOrEqual":"4.19.*","versionType":"semver"},{"version":"5.4.189","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.110","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.33","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"5.16.19","status":"unaffected","lessThanOrEqual":"5.16.*","versionType":"semver"},{"version":"5.17.2","status":"unaffected","lessThanOrEqual":"5.17.*","versionType":"semver"},{"version":"5.18","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ubifs/dir.c"]}],"references":["https://git.kernel.org/stable/c/9dddc8211430fb851ddf0b168e3a00c6f66cc185","https://git.kernel.org/stable/c/37bdf1ad592555ecda1d55b89f6e393e4c0589d1","https://git.kernel.org/stable/c/83e42a78428fc354f5e2049935b84c8d8d29b787","https://git.kernel.org/stable/c/c58af8564a7b08757173009030b74baf4b2b762b","https://git.kernel.org/stable/c/70e9090acc32348cedc5def0cd6d5c126efc97b9","https://git.kernel.org/stable/c/8b278c8dcfb565cb65eceb62a38cbf7a7c326db5","https://git.kernel.org/stable/c/afd427048047e8efdedab30e8888044e2be5aa9c"],"weaknesses":["CWE-667"],"ingestedAt":"2026-10-29T19:49:19.404Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2021/47xxx/CVE-2021-47637.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2021-47637","state":"PUBLISHED","datePublished":"2025-02-26T01:54:10.709Z","dateUpdated":"2026-05-11T13:58:14.868Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-02-26T01:48:21.519Z"},"containers":{"cna":{"title":"ubifs: Fix deadlock in concurrent rename whiteout and inode writeback","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   ↑\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)."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"9e0a1fff8db56eaaebb74b4a3ef65f86811c4798","status":"affected","lessThan":"9dddc8211430fb851ddf0b168e3a00c6f66cc185","versionType":"git"},{"version":"9e0a1fff8db56eaaebb74b4a3ef65f86811c4798","status":"affected","lessThan":"37bdf1ad592555ecda1d55b89f6e393e4c0589d1","versionType":"git"},{"version":"9e0a1fff8db56eaaebb74b4a3ef65f86811c4798","status":"affected","lessThan":"83e42a78428fc354f5e2049935b84c8d8d29b787","versionType":"git"},{"version":"9e0a1fff8db56eaaebb74b4a3ef65f86811c4798","status":"affected","lessThan":"c58af8564a7b08757173009030b74baf4b2b762b","versionType":"git"},{"version":"9e0a1fff8db56eaaebb74b4a3ef65f86811c4798","status":"affected","lessThan":"70e9090acc32348cedc5def0cd6d5c126efc97b9","versionType":"git"},{"version":"9e0a1fff8db56eaaebb74b4a3ef65f86811c4798","status":"affected","lessThan":"8b278c8dcfb565cb65eceb62a38cbf7a7c326db5","versionType":"git"},{"version":"9e0a1fff8db56eaaebb74b4a3ef65f86811c4798","status":"affected","lessThan":"afd427048047e8efdedab30e8888044e2be5aa9c","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ubifs/dir.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.9","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.9","versionType":"semver"},{"version":"4.19.238","status":"unaffected","lessThanOrEqual":"4.19.*","versionType":"semver"},{"version":"5.4.189","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.110","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.33","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"5.16.19","status":"unaffected","lessThanOrEqual":"5.16.*","versionType":"semver"},{"version":"5.17.2","status":"unaffected","lessThanOrEqual":"5.17.*","versionType":"semver"},{"version":"5.18","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ubifs/dir.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/9dddc8211430fb851ddf0b168e3a00c6f66cc185"},{"url":"https://git.kernel.org/stable/c/37bdf1ad592555ecda1d55b89f6e393e4c0589d1"},{"url":"https://git.kernel.org/stable/c/83e42a78428fc354f5e2049935b84c8d8d29b787"},{"url":"https://git.kernel.org/stable/c/c58af8564a7b08757173009030b74baf4b2b762b"},{"url":"https://git.kernel.org/stable/c/70e9090acc32348cedc5def0cd6d5c126efc97b9"},{"url":"https://git.kernel.org/stable/c/8b278c8dcfb565cb65eceb62a38cbf7a7c326db5"},{"url":"https://git.kernel.org/stable/c/afd427048047e8efdedab30e8888044e2be5aa9c"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T13:58:14.868Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"4.19.238"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"5.4.189"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"5.10.110"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"5.15.33"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"5.16.19"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"5.17.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9","versionEndExcluding":"5.18"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":5.5,"attackVector":"LOCAL","baseSeverity":"MEDIUM","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","integrityImpact":"NONE","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"LOW","confidentialityImpact":"NONE"}},{"other":{"type":"ssvc","content":{"id":"CVE-2021-47637","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2025-10-01T19:50:51.071622Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-667","lang":"en","type":"CWE","description":"CWE-667 Improper Locking"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2025-10-01T19:57:08.665Z"}}]}}}