{"api_version":"1","generated_at":"2026-09-12T03:12:57+00:00","cve":"CVE-2026-89767","urls":{"html":"https://cve.report/CVE-2026-89767","api":"https://cve.report/api/cve/CVE-2026-89767.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89767","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89767"},"summary":{"title":"ovl: fix double end_creating() on the casefold-mismatch path","description":"In the Linux kernel, the following vulnerability has been resolved:\n\novl: fix double end_creating() on the casefold-mismatch path\n\novl_create_real() releases the new dentry twice when the casefold\nconsistency check fails.  The S_IFDIR branch calls end_creating() and\nsets err, then falls through to the common out: label which calls\nend_creating() on the same dentry again:\n\n\tcase S_IFDIR:\n\t\tnewdentry = ovl_do_mkdir(ofs, dir, newdentry, attr->mode);\n\t\terr = PTR_ERR_OR_ZERO(newdentry);\n\t\tif (!err && ofs->casefold != ovl_dentry_casefolded(newdentry)) {\n\t\t\tpr_warn_ratelimited(...);\n\t\t\tend_creating(newdentry);\t/* first */\n\t\t\terr = -EINVAL;\n\t\t}\n\t\tbreak;\n\t...\n\tif (err)\n\t\tgoto out;\n\t...\n out:\n\tif (err) {\n\t\tend_creating(newdentry);\t/* second, same dentry */\n\t\treturn ERR_PTR(err);\n\t}\n\nend_creating() is end_dirop(), which does inode_unlock() on the parent\nand dput() on the dentry, so the parent directory's i_rwsem is unlocked\ntwice and the dentry is put twice.  The second unlock releases a lock\nthat is not held, which is what wedges every later creation under that\nparent, and the second dput() drops a reference that was never taken.\n\nThe branch was added by commit dfc7da402ccc (\"ovl: Check for casefold\nconsistency when creating new dentries\") as a bare dput(), which already\nreleased the reference twice; commit fe497f0759e0 (\"VFS: change\nvfs_mkdir() to unlock on failure.\") converted both sites to\nend_creating(), adding the double unlock.\n\nThis is reachable by an unprivileged user.  The casefold consistency of\nthe layers is validated at mount time in ovl_parse_layer(), and again on\nevery lookup in ovl_lookup_single(), but ofs->workdir is the internal\n\"work\" subdirectory created inside the user-supplied workdir, and that\nsubdirectory is not re-checked.  Marking it casefolded after the mount\ntherefore makes every ovl_create_temp() inherit the wrong state - and\nthat path reaches ovl_create_real() through ovl_start_creating_temp(),\nwhich uses start_creating() with a generated name and so never runs the\nlookup-time check.\n\n  unshare -Urm\n  mount -t tmpfs -o casefold=utf8-12.1.0 tmpfs mnt\n  mkdir -p mnt/lower/d mnt/upper mnt/work mnt/merged\n  mount -t overlay ovl -o lowerdir=mnt/lower,\\\n        upperdir=mnt/upper,workdir=mnt/work mnt/merged\n  chattr +F mnt/work/work\n  mkdir mnt/merged/d/sub\t\t# directory copy-up\n\n  overlayfs: wrong inherited casefold (work/#5)\n\nand the next copy-up blocks forever on the parent's i_rwsem:\n\n  mkdir           D  start_creating+0x65/0xb0\n                     ovl_start_creating_temp+0xb0/0xe0 [overlay]\n                     ovl_create_temp+0xa3/0x1d0 [overlay]\n                     ovl_copy_up_one+0x1f1c/0x21c0 [overlay]\n                     ovl_copy_up_flags+0xf5/0x140 [overlay]\n                     ovl_create_object+0xb7/0x220 [overlay]\n                     ovl_mkdir+0x23/0x40 [overlay]\n\nDrop the end_creating() from the branch and let out: own the cleanup,\nwhich is what every other error path in this function already does.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-11 20:20:07","updated_at":"2026-09-11 20:20:07"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/2fa220bc0f84597cb6de665e5b5021c5901ddf00","name":"https://git.kernel.org/stable/c/2fa220bc0f84597cb6de665e5b5021c5901ddf00","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b1aa8ab78a8e87aee9e306971465408e059f839a","name":"https://git.kernel.org/stable/c/b1aa8ab78a8e87aee9e306971465408e059f839a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/077ab8985ee278c3d8618182d335b0f0cd919e16","name":"https://git.kernel.org/stable/c/077ab8985ee278c3d8618182d335b0f0cd919e16","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89767","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89767","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected dfc7da402ccc92d6e4b01a4778a3f15f2496b9af 2fa220bc0f84597cb6de665e5b5021c5901ddf00 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected dfc7da402ccc92d6e4b01a4778a3f15f2496b9af b1aa8ab78a8e87aee9e306971465408e059f839a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected dfc7da402ccc92d6e4b01a4778a3f15f2496b9af 077ab8985ee278c3d8618182d335b0f0cd919e16 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.18","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.51 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.4 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/overlayfs/dir.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"2fa220bc0f84597cb6de665e5b5021c5901ddf00","status":"affected","version":"dfc7da402ccc92d6e4b01a4778a3f15f2496b9af","versionType":"git"},{"lessThan":"b1aa8ab78a8e87aee9e306971465408e059f839a","status":"affected","version":"dfc7da402ccc92d6e4b01a4778a3f15f2496b9af","versionType":"git"},{"lessThan":"077ab8985ee278c3d8618182d335b0f0cd919e16","status":"affected","version":"dfc7da402ccc92d6e4b01a4778a3f15f2496b9af","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/overlayfs/dir.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.18"},{"lessThan":"6.18","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.51","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.4","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.51","versionStartIncluding":"6.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.4","versionStartIncluding":"6.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"6.18","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\novl: fix double end_creating() on the casefold-mismatch path\n\novl_create_real() releases the new dentry twice when the casefold\nconsistency check fails.  The S_IFDIR branch calls end_creating() and\nsets err, then falls through to the common out: label which calls\nend_creating() on the same dentry again:\n\n\tcase S_IFDIR:\n\t\tnewdentry = ovl_do_mkdir(ofs, dir, newdentry, attr->mode);\n\t\terr = PTR_ERR_OR_ZERO(newdentry);\n\t\tif (!err && ofs->casefold != ovl_dentry_casefolded(newdentry)) {\n\t\t\tpr_warn_ratelimited(...);\n\t\t\tend_creating(newdentry);\t/* first */\n\t\t\terr = -EINVAL;\n\t\t}\n\t\tbreak;\n\t...\n\tif (err)\n\t\tgoto out;\n\t...\n out:\n\tif (err) {\n\t\tend_creating(newdentry);\t/* second, same dentry */\n\t\treturn ERR_PTR(err);\n\t}\n\nend_creating() is end_dirop(), which does inode_unlock() on the parent\nand dput() on the dentry, so the parent directory's i_rwsem is unlocked\ntwice and the dentry is put twice.  The second unlock releases a lock\nthat is not held, which is what wedges every later creation under that\nparent, and the second dput() drops a reference that was never taken.\n\nThe branch was added by commit dfc7da402ccc (\"ovl: Check for casefold\nconsistency when creating new dentries\") as a bare dput(), which already\nreleased the reference twice; commit fe497f0759e0 (\"VFS: change\nvfs_mkdir() to unlock on failure.\") converted both sites to\nend_creating(), adding the double unlock.\n\nThis is reachable by an unprivileged user.  The casefold consistency of\nthe layers is validated at mount time in ovl_parse_layer(), and again on\nevery lookup in ovl_lookup_single(), but ofs->workdir is the internal\n\"work\" subdirectory created inside the user-supplied workdir, and that\nsubdirectory is not re-checked.  Marking it casefolded after the mount\ntherefore makes every ovl_create_temp() inherit the wrong state - and\nthat path reaches ovl_create_real() through ovl_start_creating_temp(),\nwhich uses start_creating() with a generated name and so never runs the\nlookup-time check.\n\n  unshare -Urm\n  mount -t tmpfs -o casefold=utf8-12.1.0 tmpfs mnt\n  mkdir -p mnt/lower/d mnt/upper mnt/work mnt/merged\n  mount -t overlay ovl -o lowerdir=mnt/lower,\\\n        upperdir=mnt/upper,workdir=mnt/work mnt/merged\n  chattr +F mnt/work/work\n  mkdir mnt/merged/d/sub\t\t# directory copy-up\n\n  overlayfs: wrong inherited casefold (work/#5)\n\nand the next copy-up blocks forever on the parent's i_rwsem:\n\n  mkdir           D  start_creating+0x65/0xb0\n                     ovl_start_creating_temp+0xb0/0xe0 [overlay]\n                     ovl_create_temp+0xa3/0x1d0 [overlay]\n                     ovl_copy_up_one+0x1f1c/0x21c0 [overlay]\n                     ovl_copy_up_flags+0xf5/0x140 [overlay]\n                     ovl_create_object+0xb7/0x220 [overlay]\n                     ovl_mkdir+0x23/0x40 [overlay]\n\nDrop the end_creating() from the branch and let out: own the cleanup,\nwhich is what every other error path in this function already does."}],"providerMetadata":{"dateUpdated":"2026-09-11T19:47:07.353Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/2fa220bc0f84597cb6de665e5b5021c5901ddf00"},{"url":"https://git.kernel.org/stable/c/b1aa8ab78a8e87aee9e306971465408e059f839a"},{"url":"https://git.kernel.org/stable/c/077ab8985ee278c3d8618182d335b0f0cd919e16"}],"title":"ovl: fix double end_creating() on the casefold-mismatch path","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89767","datePublished":"2026-09-11T19:47:07.353Z","dateReserved":"2026-09-11T19:38:34.764Z","dateUpdated":"2026-09-11T19:47:07.353Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-11 20:20:07","lastModifiedDate":"2026-09-11 20:20:07","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89767","Ordinal":"1","Title":"ovl: fix double end_creating() on the casefold-mismatch path","CVE":"CVE-2026-89767","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89767","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\novl: fix double end_creating() on the casefold-mismatch path\n\novl_create_real() releases the new dentry twice when the casefold\nconsistency check fails.  The S_IFDIR branch calls end_creating() and\nsets err, then falls through to the common out: label which calls\nend_creating() on the same dentry again:\n\n\tcase S_IFDIR:\n\t\tnewdentry = ovl_do_mkdir(ofs, dir, newdentry, attr->mode);\n\t\terr = PTR_ERR_OR_ZERO(newdentry);\n\t\tif (!err && ofs->casefold != ovl_dentry_casefolded(newdentry)) {\n\t\t\tpr_warn_ratelimited(...);\n\t\t\tend_creating(newdentry);\t/* first */\n\t\t\terr = -EINVAL;\n\t\t}\n\t\tbreak;\n\t...\n\tif (err)\n\t\tgoto out;\n\t...\n out:\n\tif (err) {\n\t\tend_creating(newdentry);\t/* second, same dentry */\n\t\treturn ERR_PTR(err);\n\t}\n\nend_creating() is end_dirop(), which does inode_unlock() on the parent\nand dput() on the dentry, so the parent directory's i_rwsem is unlocked\ntwice and the dentry is put twice.  The second unlock releases a lock\nthat is not held, which is what wedges every later creation under that\nparent, and the second dput() drops a reference that was never taken.\n\nThe branch was added by commit dfc7da402ccc (\"ovl: Check for casefold\nconsistency when creating new dentries\") as a bare dput(), which already\nreleased the reference twice; commit fe497f0759e0 (\"VFS: change\nvfs_mkdir() to unlock on failure.\") converted both sites to\nend_creating(), adding the double unlock.\n\nThis is reachable by an unprivileged user.  The casefold consistency of\nthe layers is validated at mount time in ovl_parse_layer(), and again on\nevery lookup in ovl_lookup_single(), but ofs->workdir is the internal\n\"work\" subdirectory created inside the user-supplied workdir, and that\nsubdirectory is not re-checked.  Marking it casefolded after the mount\ntherefore makes every ovl_create_temp() inherit the wrong state - and\nthat path reaches ovl_create_real() through ovl_start_creating_temp(),\nwhich uses start_creating() with a generated name and so never runs the\nlookup-time check.\n\n  unshare -Urm\n  mount -t tmpfs -o casefold=utf8-12.1.0 tmpfs mnt\n  mkdir -p mnt/lower/d mnt/upper mnt/work mnt/merged\n  mount -t overlay ovl -o lowerdir=mnt/lower,\\\n        upperdir=mnt/upper,workdir=mnt/work mnt/merged\n  chattr +F mnt/work/work\n  mkdir mnt/merged/d/sub\t\t# directory copy-up\n\n  overlayfs: wrong inherited casefold (work/#5)\n\nand the next copy-up blocks forever on the parent's i_rwsem:\n\n  mkdir           D  start_creating+0x65/0xb0\n                     ovl_start_creating_temp+0xb0/0xe0 [overlay]\n                     ovl_create_temp+0xa3/0x1d0 [overlay]\n                     ovl_copy_up_one+0x1f1c/0x21c0 [overlay]\n                     ovl_copy_up_flags+0xf5/0x140 [overlay]\n                     ovl_create_object+0xb7/0x220 [overlay]\n                     ovl_mkdir+0x23/0x40 [overlay]\n\nDrop the end_creating() from the branch and let out: own the cleanup,\nwhich is what every other error path in this function already does.","Type":"Description","Title":"ovl: fix double end_creating() on the casefold-mismatch path"}]}}}