{"id":"DEBIAN-CVE-2026-64359","details":"In the Linux kernel, the following vulnerability has been resolved:  nilfs2: reject CLEAN_SEGMENTS ioctl with out-of-range segment numbers  Syzbot reported a hung task in nilfs_transaction_begin() where multiple tasks performing chmod() on a nilfs2 mount blocked for over 143 seconds waiting to acquire ns_segctor_sem for read:    INFO: task syz.0.17:5918 blocked for more than 143 seconds.   Call Trace:    schedule+0x164/0x360    rwsem_down_read_slowpath+0x6d9/0x940    down_read+0x99/0x2e0    nilfs_transaction_begin+0x364/0x710 fs/nilfs2/segment.c:221    nilfs_setattr+0x124/0x2c0 fs/nilfs2/inode.c:921    notify_change+0xc1a/0xf40    chmod_common+0x273/0x4a0    do_fchmodat+0x12d/0x230  The writer holding ns_segctor_sem was a concurrent NILFS_IOCTL_CLEAN_SEGMENTS caller, stuck inside printk while emitting per-element warnings from nilfs_sufile_updatev():     __nilfs_msg+0x373/0x450 fs/nilfs2/super.c:78    nilfs_sufile_updatev+0x21c/0x6d0 fs/nilfs2/sufile.c:186    nilfs_sufile_freev fs/nilfs2/sufile.h:93 [inline]    nilfs_free_segments fs/nilfs2/segment.c:1140 [inline]    nilfs_segctor_collect_blocks fs/nilfs2/segment.c:1261 [inline]    nilfs_segctor_do_construct+0x1f55/0x76c0    nilfs_clean_segments+0x3bd/0xa50    nilfs_ioctl_clean_segments fs/nilfs2/ioctl.c:922 [inline]    nilfs_ioctl+0x261f/0x2780  The root cause is that user-supplied segment numbers are not validated before nilfs_clean_segments() begins doing work; the range check on each segnum is performed deep inside the call chain by nilfs_sufile_updatev(), which emits a nilfs_warn() per invalid entry while still holding the segctor lock and the sufile mi_sem.  Under load (repeated invocations across multiple mounts saturating the global printk path), the cumulative printk latency keeps ns_segctor_sem held long enough to trip the hung_task watchdog, blocking concurrent operations such as chmod() that need ns_segctor_sem for read.  Fix by validating the contents of kbufs[4] in nilfs_clean_segments() immediately after acquiring ns_segctor_sem via nilfs_transaction_lock(). Holding ns_segctor_sem serializes the check against nilfs_ioctl_resize(), which can modify ns_nsegments, so the validation uses a consistent value.  Out-of-range segment numbers are rejected with -EINVAL before any segment-cleaning work begins, so the bad entries never reach the per-element diagnostic path inside nilfs_sufile_updatev().","modified":"2026-09-05T09:00:18.534136549Z","published":"2026-07-25T10:17:18.377Z","upstream":["CVE-2026-64359"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-64359"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.180-1"}]}],"versions":["6.1.106-1","6.1.106-2","6.1.106-3","6.1.112-1","6.1.115-1","6.1.119-1","6.1.123-1","6.1.124-1","6.1.128-1","6.1.129-1","6.1.133-1","6.1.135-1","6.1.137-1","6.1.139-1","6.1.140-1","6.1.147-1","6.1.148-1","6.1.153-1","6.1.158-1","6.1.159-1","6.1.162-1","6.1.164-1","6.1.170-1","6.1.170-2","6.1.170-3","6.1.172-1","6.1.174-1","6.1.176-1","6.1.177-1","6.1.27-1","6.1.37-1","6.1.38-1","6.1.38-2","6.1.38-2~bpo11+1","6.1.38-3","6.1.38-4","6.1.38-4~bpo11+1","6.1.52-1","6.1.55-1","6.1.55-1~bpo11+1","6.1.64-1","6.1.66-1","6.1.67-1","6.1.69-1","6.1.69-1~bpo11+1","6.1.76-1","6.1.76-1~bpo11+1","6.1.82-1","6.1.85-1","6.1.90-1","6.1.90-1~bpo11+1","6.1.94-1","6.1.94-1~bpo11+1","6.1.98-1","6.1.99-1"],"ecosystem_specific":{"urgency":"not 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