{"id":"CVE-2026-64359","state":"PUBLISHED","title":"nilfs2: reject CLEAN_SEGMENTS ioctl with out-of-range segment numbers","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnilfs2: reject CLEAN_SEGMENTS ioctl with out-of-range segment numbers\n\nSyzbot reported a hung task in nilfs_transaction_begin() where multiple\ntasks performing chmod() on a nilfs2 mount blocked for over 143 seconds\nwaiting to acquire ns_segctor_sem for read:\n\n  INFO: task syz.0.17:5918 blocked for more than 143 seconds.\n  Call Trace:\n   schedule+0x164/0x360\n   rwsem_down_read_slowpath+0x6d9/0x940\n   down_read+0x99/0x2e0\n   nilfs_transaction_begin+0x364/0x710 fs/nilfs2/segment.c:221\n   nilfs_setattr+0x124/0x2c0 fs/nilfs2/inode.c:921\n   notify_change+0xc1a/0xf40\n   chmod_common+0x273/0x4a0\n   do_fchmodat+0x12d/0x230\n\nThe writer holding ns_segctor_sem was a concurrent\nNILFS_IOCTL_CLEAN_SEGMENTS caller, stuck inside printk while emitting\nper-element warnings from nilfs_sufile_updatev():\n\n   __nilfs_msg+0x373/0x450 fs/nilfs2/super.c:78\n   nilfs_sufile_updatev+0x21c/0x6d0 fs/nilfs2/sufile.c:186\n   nilfs_sufile_freev fs/nilfs2/sufile.h:93 [inline]\n   nilfs_free_segments fs/nilfs2/segment.c:1140 [inline]\n   nilfs_segctor_collect_blocks fs/nilfs2/segment.c:1261 [inline]\n   nilfs_segctor_do_construct+0x1f55/0x76c0\n   nilfs_clean_segments+0x3bd/0xa50\n   nilfs_ioctl_clean_segments fs/nilfs2/ioctl.c:922 [inline]\n   nilfs_ioctl+0x261f/0x2780\n\nThe root cause is that user-supplied segment numbers are not validated\nbefore nilfs_clean_segments() begins doing work; the range check on\neach segnum is performed deep inside the call chain by\nnilfs_sufile_updatev(), which emits a nilfs_warn() per invalid entry\nwhile still holding the segctor lock and the sufile mi_sem.  Under load\n(repeated invocations across multiple mounts saturating the global\nprintk path), the cumulative printk latency keeps ns_segctor_sem held\nlong enough to trip the hung_task watchdog, blocking concurrent\noperations such as chmod() that need ns_segctor_sem for read.\n\nFix by validating the contents of kbufs[4] in nilfs_clean_segments()\nimmediately after acquiring ns_segctor_sem via nilfs_transaction_lock().\nHolding ns_segctor_sem serializes the check against\nnilfs_ioctl_resize(), which can modify ns_nsegments, so the validation\nuses a consistent value.  Out-of-range segment numbers are rejected\nwith -EINVAL before any segment-cleaning work begins, so the bad\nentries never reach the per-element diagnostic path inside\nnilfs_sufile_updatev().","publishedAt":"2026-07-25T08:50:15.947Z","updatedAt":"2026-08-17T04:54:05.599Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"071cb4b81987a28c7ac2702003cff3e61684a630","status":"affected","lessThan":"3ed388ec3b8922383d1e2d4432d7bd4cbbf8364e","versionType":"git"},{"version":"071cb4b81987a28c7ac2702003cff3e61684a630","status":"affected","lessThan":"876c98e0fc65f071680c03c2e2ee3ef7ff9ca078","versionType":"git"},{"version":"071cb4b81987a28c7ac2702003cff3e61684a630","status":"affected","lessThan":"39607452b1400c7bf748f15122df4d058b768c5b","versionType":"git"},{"version":"071cb4b81987a28c7ac2702003cff3e61684a630","status":"affected","lessThan":"286f77d002a337735c0846d7480a82d9cda2aa31","versionType":"git"},{"version":"071cb4b81987a28c7ac2702003cff3e61684a630","status":"affected","lessThan":"0789f0a6710713254a08f3a7d2ecbb6d1cbcf0aa","versionType":"git"},{"version":"071cb4b81987a28c7ac2702003cff3e61684a630","status":"affected","lessThan":"223463c488b0554212a94de971ea538eb2805fc7","versionType":"git"},{"version":"071cb4b81987a28c7ac2702003cff3e61684a630","status":"affected","lessThan":"d26aef771b4f6923da9f89d6d5b70d8def5853de","versionType":"git"},{"version":"071cb4b81987a28c7ac2702003cff3e61684a630","status":"affected","lessThan":"0e7a690fe435f8d5ea3feb7c1d8d73ba7e8b8aa9","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nilfs2/segment.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.31","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.31","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.96","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nilfs2/segment.c"]}],"references":["https://git.kernel.org/stable/c/3ed388ec3b8922383d1e2d4432d7bd4cbbf8364e","https://git.kernel.org/stable/c/876c98e0fc65f071680c03c2e2ee3ef7ff9ca078","https://git.kernel.org/stable/c/39607452b1400c7bf748f15122df4d058b768c5b","https://git.kernel.org/stable/c/286f77d002a337735c0846d7480a82d9cda2aa31","https://git.kernel.org/stable/c/0789f0a6710713254a08f3a7d2ecbb6d1cbcf0aa","https://git.kernel.org/stable/c/223463c488b0554212a94de971ea538eb2805fc7","https://git.kernel.org/stable/c/d26aef771b4f6923da9f89d6d5b70d8def5853de","https://git.kernel.org/stable/c/0e7a690fe435f8d5ea3feb7c1d8d73ba7e8b8aa9"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64359.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64359","state":"PUBLISHED","datePublished":"2026-07-25T08:50:15.947Z","dateUpdated":"2026-08-17T04:54:05.599Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T15:36:31.782Z"},"containers":{"cna":{"title":"nilfs2: reject CLEAN_SEGMENTS ioctl with out-of-range segment numbers","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnilfs2: reject CLEAN_SEGMENTS ioctl with out-of-range segment numbers\n\nSyzbot reported a hung task in nilfs_transaction_begin() where multiple\ntasks performing chmod() on a nilfs2 mount blocked for over 143 seconds\nwaiting to acquire ns_segctor_sem for read:\n\n  INFO: task syz.0.17:5918 blocked for more than 143 seconds.\n  Call Trace:\n   schedule+0x164/0x360\n   rwsem_down_read_slowpath+0x6d9/0x940\n   down_read+0x99/0x2e0\n   nilfs_transaction_begin+0x364/0x710 fs/nilfs2/segment.c:221\n   nilfs_setattr+0x124/0x2c0 fs/nilfs2/inode.c:921\n   notify_change+0xc1a/0xf40\n   chmod_common+0x273/0x4a0\n   do_fchmodat+0x12d/0x230\n\nThe writer holding ns_segctor_sem was a concurrent\nNILFS_IOCTL_CLEAN_SEGMENTS caller, stuck inside printk while emitting\nper-element warnings from nilfs_sufile_updatev():\n\n   __nilfs_msg+0x373/0x450 fs/nilfs2/super.c:78\n   nilfs_sufile_updatev+0x21c/0x6d0 fs/nilfs2/sufile.c:186\n   nilfs_sufile_freev fs/nilfs2/sufile.h:93 [inline]\n   nilfs_free_segments fs/nilfs2/segment.c:1140 [inline]\n   nilfs_segctor_collect_blocks fs/nilfs2/segment.c:1261 [inline]\n   nilfs_segctor_do_construct+0x1f55/0x76c0\n   nilfs_clean_segments+0x3bd/0xa50\n   nilfs_ioctl_clean_segments fs/nilfs2/ioctl.c:922 [inline]\n   nilfs_ioctl+0x261f/0x2780\n\nThe root cause is that user-supplied segment numbers are not validated\nbefore nilfs_clean_segments() begins doing work; the range check on\neach segnum is performed deep inside the call chain by\nnilfs_sufile_updatev(), which emits a nilfs_warn() per invalid entry\nwhile still holding the segctor lock and the sufile mi_sem.  Under load\n(repeated invocations across multiple mounts saturating the global\nprintk path), the cumulative printk latency keeps ns_segctor_sem held\nlong enough to trip the hung_task watchdog, blocking concurrent\noperations such as chmod() that need ns_segctor_sem for read.\n\nFix by validating the contents of kbufs[4] in nilfs_clean_segments()\nimmediately after acquiring ns_segctor_sem via nilfs_transaction_lock().\nHolding ns_segctor_sem serializes the check against\nnilfs_ioctl_resize(), which can modify ns_nsegments, so the validation\nuses a consistent value.  Out-of-range segment numbers are rejected\nwith -EINVAL before any segment-cleaning work begins, so the bad\nentries never reach the per-element diagnostic path inside\nnilfs_sufile_updatev()."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"071cb4b81987a28c7ac2702003cff3e61684a630","status":"affected","lessThan":"3ed388ec3b8922383d1e2d4432d7bd4cbbf8364e","versionType":"git"},{"version":"071cb4b81987a28c7ac2702003cff3e61684a630","status":"affected","lessThan":"876c98e0fc65f071680c03c2e2ee3ef7ff9ca078","versionType":"git"},{"version":"071cb4b81987a28c7ac2702003cff3e61684a630","status":"affected","lessThan":"39607452b1400c7bf748f15122df4d058b768c5b","versionType":"git"},{"version":"071cb4b81987a28c7ac2702003cff3e61684a630","status":"affected","lessThan":"286f77d002a337735c0846d7480a82d9cda2aa31","versionType":"git"},{"version":"071cb4b81987a28c7ac2702003cff3e61684a630","status":"affected","lessThan":"0789f0a6710713254a08f3a7d2ecbb6d1cbcf0aa","versionType":"git"},{"version":"071cb4b81987a28c7ac2702003cff3e61684a630","status":"affected","lessThan":"223463c488b0554212a94de971ea538eb2805fc7","versionType":"git"},{"version":"071cb4b81987a28c7ac2702003cff3e61684a630","status":"affected","lessThan":"d26aef771b4f6923da9f89d6d5b70d8def5853de","versionType":"git"},{"version":"071cb4b81987a28c7ac2702003cff3e61684a630","status":"affected","lessThan":"0e7a690fe435f8d5ea3feb7c1d8d73ba7e8b8aa9","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nilfs2/segment.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.31","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.31","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.96","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nilfs2/segment.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/3ed388ec3b8922383d1e2d4432d7bd4cbbf8364e"},{"url":"https://git.kernel.org/stable/c/876c98e0fc65f071680c03c2e2ee3ef7ff9ca078"},{"url":"https://git.kernel.org/stable/c/39607452b1400c7bf748f15122df4d058b768c5b"},{"url":"https://git.kernel.org/stable/c/286f77d002a337735c0846d7480a82d9cda2aa31"},{"url":"https://git.kernel.org/stable/c/0789f0a6710713254a08f3a7d2ecbb6d1cbcf0aa"},{"url":"https://git.kernel.org/stable/c/223463c488b0554212a94de971ea538eb2805fc7"},{"url":"https://git.kernel.org/stable/c/d26aef771b4f6923da9f89d6d5b70d8def5853de"},{"url":"https://git.kernel.org/stable/c/0e7a690fe435f8d5ea3feb7c1d8d73ba7e8b8aa9"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T04:54:05.599Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.31","versionEndExcluding":"5.10.261"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.31","versionEndExcluding":"5.15.212"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.31","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.31","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.31","versionEndExcluding":"6.12.96"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.31","versionEndExcluding":"6.18.39"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.31","versionEndExcluding":"7.1.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.31","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}