{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2021-46989","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2024-02-27T18:42:55.948Z","datePublished":"2024-02-28T08:13:15.930Z","dateUpdated":"2026-08-05T08:45:24.640Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T08:45:24.640Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nhfsplus: prevent corruption in shrinking truncate\n\nI believe there are some issues introduced by commit 31651c607151\n(\"hfsplus: avoid deadlock on file truncation\")\n\nHFS+ has extent records which always contains 8 extents.  In case the\nfirst extent record in catalog file gets full, new ones are allocated from\nextents overflow file.\n\nIn case shrinking truncate happens to middle of an extent record which\nlocates in extents overflow file, the logic in hfsplus_file_truncate() was\nchanged so that call to hfs_brec_remove() is not guarded any more.\n\nRight action would be just freeing the extents that exceed the new size\ninside extent record by calling hfsplus_free_extents(), and then check if\nthe whole extent record should be removed.  However since the guard\n(blk_cnt > start) is now after the call to hfs_brec_remove(), this has\nunfortunate effect that the last matching extent record is removed\nunconditionally.\n\nTo reproduce this issue, create a file which has at least 10 extents, and\nthen perform shrinking truncate into middle of the last extent record, so\nthat the number of remaining extents is not under or divisible by 8.  This\ncauses the last extent record (8 extents) to be removed totally instead of\ntruncating into middle of it.  Thus this causes corruption, and lost data.\n\nFix for this is simply checking if the new truncated end is below the\nstart of this extent record, making it safe to remove the full extent\nrecord.  However call to hfs_brec_remove() can't be moved to it's previous\nplace since we're dropping ->tree_lock and it can cause a race condition\nand the cached info being invalidated possibly corrupting the node data.\n\nAnother issue is related to this one.  When entering into the block\n(blk_cnt > start) we are not holding the ->tree_lock.  We break out from\nthe loop not holding the lock, but hfs_find_exit() does unlock it.  Not\nsure if it's possible for someone else to take the lock under our feet,\nbut it can cause hard to debug errors and premature unlocking.  Even if\nthere's no real risk of it, the locking should still always be kept in\nbalance.  Thus taking the lock now just before the check."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H","baseScore":7.1,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerable path is reached via local VFS truncate/setattr (ftruncate/truncate → notify_change → hfsplus_setattr → hfsplus_file_truncate) on a mounted HFS+ volume, not via network packet processing or an in-kernel network filesystem server.\nAC:L - An attacker who can write can create a file with ≥10 extents and shrink-truncate into the middle of the last overflow extent record; the incorrect hfs_brec_remove() and the tree_lock unlock imbalance both occur deterministically with no attacker-uncontrollable race or layout requirement.\nPR:L - Triggering requires only write access to a file on an already-mounted writable HFS+ filesystem (MAY_WRITE / writable fd); mounting HFS+ is an admin/deployment precondition, not an attacker privilege, matching prior local filesystem scoring.\nUI:N - The attacker drives fragmentation and the shrinking truncate on their own files; no separate victim action such as mounting a crafted image or opening a malicious file is required.\nS:U - Impact is confined to the host kernel and the mounted HFS+ filesystem authority (metadata corruption and lock imbalance); it does not cross a VM, IOMMU, or other security boundary.\nC:N - The defect wrongly removes extent overflow records and imbalances tree_lock, causing data loss and possible concurrent btree races, but does not provide an OOB/UAF read or other established information-disclosure primitive.\nI:H - Unconditional hfs_brec_remove() deletes an entire overflow extent record that should only be partially truncated, corrupting on-disk extent metadata and losing file data as described in the fix; the same path can also unlock tree_lock while another inode’s extent ops hold it, enabling concurrent btree modification.\nA:H - Breaking out of the truncate loop without re-acquiring tree_lock causes hfs_find_exit() to mutex_unlock an already-unlocked lock (kernel WARN/oops or hang under contention), and the resulting filesystem corruption denies access to affected data/volume."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/hfsplus/extents.c"],"versions":[{"version":"31651c607151f1034cfb57e5a78678bea54c362b","lessThan":"52dde855663e5db824af51db39b5757d2ef3e28a","status":"affected","versionType":"git"},{"version":"31651c607151f1034cfb57e5a78678bea54c362b","lessThan":"c451a6bafb5f422197d31536f82116aed132b72c","status":"affected","versionType":"git"},{"version":"31651c607151f1034cfb57e5a78678bea54c362b","lessThan":"adbd8a2a8cc05d9e501f93e5c95c59307874cc99","status":"affected","versionType":"git"},{"version":"31651c607151f1034cfb57e5a78678bea54c362b","lessThan":"c477f62db1a0c0ecaa60a29713006ceeeb04b685","status":"affected","versionType":"git"},{"version":"31651c607151f1034cfb57e5a78678bea54c362b","lessThan":"97314e45aa1223a42d60256a62c5d9af54baf446","status":"affected","versionType":"git"},{"version":"31651c607151f1034cfb57e5a78678bea54c362b","lessThan":"c3187cf32216313fb316084efac4dab3a8459b1d","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/hfsplus/extents.c"],"versions":[{"version":"4.19","status":"affected"},{"version":"0","lessThan":"4.19","status":"unaffected","versionType":"semver"},{"version":"4.19.191","lessThanOrEqual":"4.19.*","status":"unaffected","versionType":"semver"},{"version":"5.4.120","lessThanOrEqual":"5.4.*","status":"unaffected","versionType":"semver"},{"version":"5.10.38","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.11.22","lessThanOrEqual":"5.11.*","status":"unaffected","versionType":"semver"},{"version":"5.12.5","lessThanOrEqual":"5.12.*","status":"unaffected","versionType":"semver"},{"version":"5.13","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"4.19.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"5.4.120"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"5.10.38"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"5.11.22"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"5.12.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"5.13"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/52dde855663e5db824af51db39b5757d2ef3e28a"},{"url":"https://git.kernel.org/stable/c/c451a6bafb5f422197d31536f82116aed132b72c"},{"url":"https://git.kernel.org/stable/c/adbd8a2a8cc05d9e501f93e5c95c59307874cc99"},{"url":"https://git.kernel.org/stable/c/c477f62db1a0c0ecaa60a29713006ceeeb04b685"},{"url":"https://git.kernel.org/stable/c/97314e45aa1223a42d60256a62c5d9af54baf446"},{"url":"https://git.kernel.org/stable/c/c3187cf32216313fb316084efac4dab3a8459b1d"}],"title":"hfsplus: prevent corruption in shrinking truncate","x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"problemTypes":[{"descriptions":[{"type":"CWE","lang":"en","description":"CWE-noinfo Not enough information"}]}],"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":{"timestamp":"2024-02-28T18:24:07.661826Z","id":"CVE-2021-46989","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2024-11-04T16:56:31.426Z"}},{"providerMetadata":{"orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE","dateUpdated":"2024-08-04T05:24:37.918Z"},"title":"CVE Program Container","references":[{"url":"https://git.kernel.org/stable/c/52dde855663e5db824af51db39b5757d2ef3e28a","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/c451a6bafb5f422197d31536f82116aed132b72c","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/adbd8a2a8cc05d9e501f93e5c95c59307874cc99","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/c477f62db1a0c0ecaa60a29713006ceeeb04b685","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/97314e45aa1223a42d60256a62c5d9af54baf446","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/c3187cf32216313fb316084efac4dab3a8459b1d","tags":["x_transferred"]}]}]}}