{"id":"DEBIAN-CVE-2023-52705","details":"In the Linux kernel, the following vulnerability has been resolved:  nilfs2: fix underflow in second superblock position calculations  Macro NILFS_SB2_OFFSET_BYTES, which computes the position of the second superblock, underflows when the argument device size is less than 4096 bytes.  Therefore, when using this macro, it is necessary to check in advance that the device size is not less than a lower limit, or at least that underflow does not occur.  The current nilfs2 implementation lacks this check, causing out-of-bound block access when mounting devices smaller than 4096 bytes:   I/O error, dev loop0, sector 36028797018963960 op 0x0:(READ) flags 0x0  phys_seg 1 prio class 2  NILFS (loop0): unable to read secondary superblock (blocksize = 1024)  In addition, when trying to resize the filesystem to a size below 4096 bytes, this underflow occurs in nilfs_resize_fs(), passing a huge number of segments to nilfs_sufile_resize(), corrupting parameters such as the number of segments in superblocks.  This causes excessive loop iterations in nilfs_sufile_resize() during a subsequent resize ioctl, causing semaphore ns_segctor_sem to block for a long time and hang the writer thread:   INFO: task segctord:5067 blocked for more than 143 seconds.       Not tainted 6.2.0-rc8-syzkaller-00015-gf6feea56f66d #0  \"echo 0 \u003e /proc/sys/kernel/hung_task_timeout_secs\" disables this message.  task:segctord        state:D stack:23456 pid:5067  ppid:2  flags:0x00004000  Call Trace:   \u003cTASK\u003e   context_switch kernel/sched/core.c:5293 [inline]   __schedule+0x1409/0x43f0 kernel/sched/core.c:6606   schedule+0xc3/0x190 kernel/sched/core.c:6682   rwsem_down_write_slowpath+0xfcf/0x14a0 kernel/locking/rwsem.c:1190   nilfs_transaction_lock+0x25c/0x4f0 fs/nilfs2/segment.c:357   nilfs_segctor_thread_construct fs/nilfs2/segment.c:2486 [inline]   nilfs_segctor_thread+0x52f/0x1140 fs/nilfs2/segment.c:2570   kthread+0x270/0x300 kernel/kthread.c:376   ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308   \u003c/TASK\u003e  ...  Call Trace:   \u003cTASK\u003e   folio_mark_accessed+0x51c/0xf00 mm/swap.c:515   __nilfs_get_page_block fs/nilfs2/page.c:42 [inline]   nilfs_grab_buffer+0x3d3/0x540 fs/nilfs2/page.c:61   nilfs_mdt_submit_block+0xd7/0x8f0 fs/nilfs2/mdt.c:121   nilfs_mdt_read_block+0xeb/0x430 fs/nilfs2/mdt.c:176   nilfs_mdt_get_block+0x12d/0xbb0 fs/nilfs2/mdt.c:251   nilfs_sufile_get_segment_usage_block fs/nilfs2/sufile.c:92 [inline]   nilfs_sufile_truncate_range fs/nilfs2/sufile.c:679 [inline]   nilfs_sufile_resize+0x7a3/0x12b0 fs/nilfs2/sufile.c:777   nilfs_resize_fs+0x20c/0xed0 fs/nilfs2/super.c:422   nilfs_ioctl_resize fs/nilfs2/ioctl.c:1033 [inline]   nilfs_ioctl+0x137c/0x2440 fs/nilfs2/ioctl.c:1301   ...  This fixes these issues by inserting appropriate minimum device size checks or anti-underflow checks, depending on where the macro is used.","modified":"2026-09-15T09:02:48.612957677Z","published":"2024-05-21T16:15:12.840Z","upstream":["CVE-2023-52705"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2023-52705"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.15-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2023-52705.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.15-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2023-52705.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.15-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2023-52705.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}