{ "schema_version": "1.6.1", "id": "RPI-CVE-2025-38321", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2025-38321" ], "published": "2025-07-10T08:18:24Z", "summary": "smb: Log an error when close_all_cached_dirs fails", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: Log an error when close_all_cached_dirs fails\n\nUnder low-memory conditions, close_all_cached_dirs() can't move the\ndentries to a separate list to dput() them once the locks are dropped.\nThis will result in a \"Dentry still in use\" error, so add an error\nmessage that makes it clear this is what happened:\n\n[ 495.281119] CIFS: VFS: \\\\otters.example.com\\share Out of memory while dropping dentries\n[ 495.281595] ------------[ cut here ]------------\n[ 495.281887] BUG: Dentry ffff888115531138{i=78,n=/} still in use (2) [unmount of cifs cifs]\n[ 495.282391] WARNING: CPU: 1 PID: 2329 at fs/dcache.c:1536 umount_check+0xc8/0xf0\n\nAlso, bail out of looping through all tcons as soon as a single\nallocation fails, since we're already in trouble, and kmalloc() attempts\nfor subseqeuent tcons are likely to fail just like the first one did.", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:12", "name": "linux" }, "versions": [ "1:6.6.74-1+rpt1", "1:6.12.20-1+rpt1~bpo12+1", "1:6.12.25-1+rpt1", "1:6.12.34-1+rpt1~bookworm" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.6.74+rpt-rpi-2712", "binary_version": "1:6.6.74-1+rpt1" }, { "binary_name": "linux-image-6.6.74+rpt-rpi-v6", "binary_version": "1:6.6.74-1+rpt1" }, { "binary_name": "linux-image-6.6.74+rpt-rpi-v7", "binary_version": "1:6.6.74-1+rpt1" }, { "binary_name": "linux-image-6.6.74+rpt-rpi-v7l", "binary_version": "1:6.6.74-1+rpt1" }, { "binary_name": "linux-image-6.6.74+rpt-rpi-v8", "binary_version": "1:6.6.74-1+rpt1" }, { "binary_name": "linux-image-6.12.20+rpt-rpi-2712", 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"binary_version": "1:6.12.34-1+rpt1" } ] }, "database_specific": { "per_version": { "1:6.12.19-1+rpt1~bpo12+1": { "linux_commit": "121c2c384b9c2f4790ffb31b2cd25c7d75c8fda0", "upstream_version": "6.12.19", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.12.35" }, "1:6.12.19-1+rpt1": { "linux_commit": "121c2c384b9c2f4790ffb31b2cd25c7d75c8fda0", "upstream_version": "6.12.19", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.12.35" }, "1:6.12.20-1+rpt1": { "linux_commit": "cd231d4775b14f228606c09f219b48308f6ab3aa", "upstream_version": "6.12.20", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.12.35" }, "1:6.12.25-1+rpt1+trixie": { "linux_commit": "3dd2c2c507c271d411fab2e82a2b3b7e0b6d3f16", "upstream_version": "6.12.25", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.12.35" }, "1:6.12.34-1+rpt1": { "linux_commit": "8f77e03530f65209a377d25023e912b288e039cd", "upstream_version": "6.12.34", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.12.35" } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2025-38321" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/b8ced2b9a23a1a2c1e0ed8d0d02512e51bdf38da" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/43f26094d6702e494e800532c3f1606e7a68eb30" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/4479db143390bdcadc1561292aab579cdfa9f6c6" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/a2182743a8b4969481f64aec4908ff162e8a206c" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-05T12:19:11Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 7.8, "cvss_v3_severity": "High", "scenario": "AV:L - The vulnerable code runs only in `cifs_kill_sb()` on the local unmount path, and the triggering condition is a local GFP_ATOMIC allocation failure under memory pressure; a remote SMB server can influence how many cached dirs exist but cannot drive the unmount or the OOM.\nAC:L - Memory pressure is directly attacker-inducible and GFP_ATOMIC allocations fail readily under it, and the mount/unmount cycle can be repeated indefinitely, with up to `max_cached_dirs` allocations per tcon per unmount (multiplied further by `multiuser` mounts) giving many independent chances to hit the failure.\nPR:L - A basic unprivileged local account suffices to create the memory pressure, and the unmount is reachable to the same user through the standard `user`/`users` fstab option for SMB shares, setuid `mount.cifs`, or an autofs/systemd idle-expiry unmount; no root or CAP_SYS_ADMIN in the init namespace is required.\nUI:N - On user-mountable shares the attacker performs the mount, the memory exhaustion, and the unmount entirely from their own process, and on automounted shares the expiry unmount happens on a timer with no victim action at all.\nS:U - The leaked dentries, poisoned inodes, and freed superblock are all kernel objects within the same security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - When the tcon is shared with a surviving superblock, the undropped `cfid->dentry` outlives `destroy_super()`, so the later `dput()` reads `dentry->d_sb` fields (`s_dentry_lru`, `s_d_op`, `s_type`) out of a freed kmalloc-2k object the attacker can reoccupy, giving a use-after-free read primitive over sprayed heap contents.\nI:H - The same dangling `dput()` performs list operations on the freed superblock's `s_dentry_lru`, writing into attacker-groomed heap memory, and the VFS additionally overwrites `i_op`/`i_sb`/`i_mapping` of the still-referenced inodes \u2014 a use-after-free write primitive usable for control-flow corruption.\nA:H - The failure deterministically produces `WARN(1, \"BUG: Dentry ... still in use\")` in `umount_check()` (a panic under `panic_on_warn`), then `CHECK_DATA_CORRUPTION()` on busy inodes which is an outright `BUG()` with `CONFIG_BUG_ON_DATA_CORRUPTION=y`, and otherwise poisons the inodes so the subsequent `iput_final()` oopses on `VFS_PTR_POISON`." } } }