{"cve":"CVE-2025-39885","nvd":{"published":"2025-09-23T06:15:48.370","modified":"2026-10-19T21:10:00.160","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: fix recursive semaphore deadlock in fiemap call\n\nsyzbot detected a OCFS2 hang due to a recursive semaphore on a\nFS_IOC_FIEMAP of the extent list on a specially crafted mmap file.\n\ncontext_switch kernel/sched/core.c:5357 [inline]\n   __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961\n   __schedule_loop kernel/sched/core.c:7043 [inline]\n   schedule+0x165/0x360 kernel/sched/core.c:7058\n   schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115\n   rwsem_down_write_slowpath+0x872/0xfe0 kernel/locking/rwsem.c:1185\n   __down_write_common kernel/locking/rwsem.c:1317 [inline]\n   __down_write kernel/locking/rwsem.c:1326 [inline]\n   down_write+0x1ab/0x1f0 kernel/locking/rwsem.c:1591\n   ocfs2_page_mkwrite+0x2ff/0xc40 fs/ocfs2/mmap.c:142\n   do_page_mkwrite+0x14d/0x310 mm/memory.c:3361\n   wp_page_shared mm/memory.c:3762 [inline]\n   do_wp_page+0x268d/0x5800 mm/memory.c:3981\n   handle_pte_fault mm/memory.c:6068 [inline]\n   __handle_mm_fault+0x1033/0x5440 mm/memory.c:6195\n   handle_mm_fault+0x40a/0x8e0 mm/memory.c:6364\n   do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1387\n   handle_page_fault arch/x86/mm/fault.c:1476 [inline]\n   exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532\n   asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623\nRIP: 0010:copy_user_generic arch/x86/include/asm/uaccess_64.h:126 [inline]\nRIP: 0010:raw_copy_to_user arch/x86/include/asm/uaccess_64.h:147 [inline]\nRIP: 0010:_inline_copy_to_user include/linux/uaccess.h:197 [inline]\nRIP: 0010:_copy_to_user+0x85/0xb0 lib/usercopy.c:26\nCode: e8 00 bc f7 fc 4d 39 fc 72 3d 4d 39 ec 77 38 e8 91 b9 f7 fc 4c 89\nf7 89 de e8 47 25 5b fd 0f 01 cb 4c 89 ff 48 89 d9 4c 89 f6 <f3> a4 0f\n1f 00 48 89 cb 0f 01 ca 48 89 d8 5b 41 5c 41 5d 41 5e 41\nRSP: 0018:ffffc9000403f950 EFLAGS: 00050256\nRAX: ffffffff84c7f101 RBX: 0000000000000038 RCX: 0000000000000038\nRDX: 0000000000000000 RSI: ffffc9000403f9e0 RDI: 0000200000000060\nRBP: ffffc9000403fa90 R08: ffffc9000403fa17 R09: 1ffff92000807f42\nR10: dffffc0000000000 R11: fffff52000807f43 R12: 0000200000000098\nR13: 00007ffffffff000 R14: ffffc9000403f9e0 R15: 0000200000000060\n   copy_to_user include/linux/uaccess.h:225 [inline]\n   fiemap_fill_next_extent+0x1c0/0x390 fs/ioctl.c:145\n   ocfs2_fiemap+0x888/0xc90 fs/ocfs2/extent_map.c:806\n   ioctl_fiemap fs/ioctl.c:220 [inline]\n   do_vfs_ioctl+0x1173/0x1430 fs/ioctl.c:532\n   __do_sys_ioctl fs/ioctl.c:596 [inline]\n   __se_sys_ioctl+0x82/0x170 fs/ioctl.c:584\n   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n   do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\nRIP: 0033:0x7f5f13850fd9\nRSP: 002b:00007ffe3b3518b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010\nRAX: ffffffffffffffda RBX: 0000200000000000 RCX: 00007f5f13850fd9\nRDX: 0000200000000040 RSI: 00000000c020660b RDI: 0000000000000004\nRBP: 6165627472616568 R08: 0000000000000000 R09: 0000000000000000\nR10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe3b3518f0\nR13: 00007ffe3b351b18 R14: 431bde82d7b634db R15: 00007f5f1389a03b\n\nocfs2_fiemap() takes a read lock of the ip_alloc_sem semaphore (since\nv2.6.22-527-g7307de80510a) and calls fiemap_fill_next_extent() to read the\nextent list of this running mmap executable.  The user supplied buffer to\nhold the fiemap information page faults calling ocfs2_page_mkwrite() which\nwill take a write lock (since v2.6.27-38-g00dc417fa3e7) of the same\nsemaphore.  This recursive semaphore will hold filesystem locks and causes\na hang of the fileystem.\n\nThe ip_alloc_sem protects the inode extent list and size.  Release the\nread semphore before calling fiemap_fill_next_extent() in ocfs2_fiemap()\nand ocfs2_fiemap_inline().  This does an unnecessary semaphore lock/unlock\non the last extent but simplifies the error path.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-667"],"references":["https://git.kernel.org/stable/c/04100f775c2ea501927f508f17ad824ad1f23c8d","https://git.kernel.org/stable/c/0709bc11b942870fc0a7be150e42aea42321093a","https://git.kernel.org/stable/c/16e518ca84dfe860c20a62f3615e14e8af0ace57","https://git.kernel.org/stable/c/1d3c96547ee2ddeaddf8f19a3ef99ea06cc8115e","https://git.kernel.org/stable/c/36054554772f95d090eb45793faf6aa3c0254b02"],"products":["debian:debian_linux","linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-21T03:43:09.190223697+00:00"},"epss":{"cve":"CVE-2025-39885","score":0.0012,"percentile":0.01825,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}