{ "schema_version": "1.6.1", "id": "RPI-CVE-2026-72381", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2026-72381" ], "published": "2026-08-15T06:04:33Z", "summary": "ksmbd: fix use-after-free of fp->owner.name in durable handle owner check", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free of fp->owner.name in durable handle owner check\n\nTwo concurrent SMB2 durable reconnects (DH2C/DHnC) on the same\npersistent_id race the fp->owner.name compare-read in\nksmbd_vfs_compare_durable_owner() against the kfree() in\nksmbd_reopen_durable_fd()'s reopen-success path. fp->owner.name is a\nstandalone kstrdup() buffer whose lifetime is independent of the fp\nrefcount, and the two sites share no lock: the compare reads the buffer\nwhile the reopen frees it, so the strcmp() can dereference freed memory.\n\nCommit 7ce4fc40018d (\"ksmbd: fix durable reconnect double-bind race in\nksmbd_reopen_durable_fd\") made the fp->conn claim atomic under\nglobal_ft.lock (closing the owner.name double-free and the ksmbd_file\nwrite-UAF), but the compare-read versus reopen-free pair was left\nunserialized.\n\n BUG: KASAN: slab-use-after-free in strcmp+0x2c/0x80\n Read of size 1 by task kworker\n strcmp\n ksmbd_vfs_compare_durable_owner\n smb2_check_durable_oplock\n smb2_open\n Freed by task kworker:\n kfree\n ksmbd_reopen_durable_fd\n smb2_open\n Allocated by task kworker:\n kstrdup\n session_fd_check\n smb2_session_logoff\n The buggy address belongs to the cache kmalloc-8\n\nSerialize both sides of the race with fp->f_lock. The global durable\nfile-table lock still protects the durable reconnect claim, but\nfp->owner.name is per-open state and does not need to block unrelated\ndurable table lookups or reconnects. The teardown is left at its\nexisting location after the reopen-success point so that an __open_id()\nrollback still retains owner.name for a later legitimate reconnect to\nverify.", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:12", "name": "linux" }, "versions": [ "1:6.12.93-1+rpt1", "1:6.12.96-1+rpt1" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.12.93+rpt-rpi-2712", "binary_version": "1:6.12.93-1+rpt1" }, { "binary_name": "linux-image-6.12.93+rpt-rpi-v6", "binary_version": "1:6.12.93-1+rpt1" }, { "binary_name": "linux-image-6.12.93+rpt-rpi-v7", "binary_version": "1:6.12.93-1+rpt1" }, { "binary_name": "linux-image-6.12.93+rpt-rpi-v7l", "binary_version": "1:6.12.93-1+rpt1" }, { "binary_name": "linux-image-6.12.93+rpt-rpi-v8", "binary_version": "1:6.12.93-1+rpt1" }, { "binary_name": "linux-image-6.12.93+rpt-rpi-v8-rt", "binary_version": 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"binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-v8-rt", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-2712", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v6", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v7", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v8", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v8-rt", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-2712", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v6", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v7", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v8", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v8-rt", "binary_version": "1:6.18.39-1+rpt1" } ] }, "database_specific": { "per_version": { "1:6.18.29-1+rpt1": { "linux_commit": "66318c5b5cd8145a662303af12ed39ac07eb27cc", "upstream_version": "6.18.29", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.40" }, "1:6.18.33-1+rpt1": { "linux_commit": "95b85bebbedcaedfa7ca79116ed38b7376fba412", "upstream_version": "6.18.33", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.40" }, "1:6.18.34-1+rpt1": { "linux_commit": "c8c7494100e99ee05b11aaa4f0588a223a63d1af", "upstream_version": "6.18.34", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.40" }, "1:6.18.39-1+rpt1": { "linux_commit": "60ea684a8ace97bb0db1a16e20753bdd6ab371ff", "upstream_version": "6.18.39", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.40" } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2026-72381" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/fb978d72052704c6b06c6b0f129fcd60b77169f5" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/93d4d46bf9d442a12ea87278049ec416962c627f" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/5a5ac2852cd326529d02f778bc1aa6184701f4d7" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/ed98719be41389d416953b8ef9f07a07dfea6b2b" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/38637163501fd9e2f684b8cd275d0db5d79f37c6" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-17T05:50:24Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 9.8, "cvss_v3_severity": "Critical", "scenario": "AV:N - The flaw is reached via ksmbd's in-kernel SMB2 server on TCP port 445; remote SMB2_CREATE durable-handle reconnect packets (DH2C/DHnC) traverse ksmbd_conn_handler_loop() -> smb2_check_user_session() -> smb2_open() -> parse_durable_handle_context() -> smb2_check_durable_oplock() / ksmbd_reopen_durable_fd().\nAC:L - The attacker controls both sides of the race by opening a durable handle, issuing SMB2_LOGOFF to preserve owner.name via session_fd_check(), then sending concurrent SMB2_CREATE durable reconnect requests for the same persistent_id from multiple connections; no timing or layout outside attacker control is required.\nPR:N - Exploitation requires only network reachability to ksmbd and valid SMB session credentials (guest or any share user) plus tree connect; no elevated host privileges, capabilities, or local access are needed beyond share-level SMB access obtainable through the protocol itself.\nUI:N - No victim user interaction is required beyond a server running ksmbd with durable handles enabled; the attacker programmatically drives the open, logoff, and concurrent reconnect SMB2 sequence over the network.\nS:U - Impact is confined to kernel heap memory corruption and privilege escalation within the same host security authority; this is not a VM escape, container boundary bypass, or IOMMU/DMA isolation break.\nC:H - strcmp() in ksmbd_vfs_compare_durable_owner() dereferences a freed kmalloc-8 fp->owner.name buffer while a concurrent ksmbd_reopen_durable_fd() kfree() runs; this slab use-after-free enables arbitrary kernel memory disclosure via heap reuse.\nI:H - Use-after-free of the standalone owner.name kstrdup buffer provides kernel heap corruption primitives; with heap grooming the freed slab can be reallocated for arbitrary kernel memory writes and control-flow hijacking.\nA:H - KASAN reports slab-use-after-free in strcmp on the owner.name buffer during concurrent smb2_open durable reconnects; the UAF can trigger kernel oops or panic on ksmbd worker threads and is repeatable by resending concurrent reconnect requests." } } }