fs/proc: fix uaf in proc_readdir_de()
Summary
| CVE | CVE-2025-40271 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2025-12-06 22:15:54 UTC |
| Updated | 2026-06-02 14:16:32 UTC |
| Description | In the Linux kernel, the following vulnerability has been resolved: fs/proc: fix uaf in proc_readdir_de() Pde is erased from subdir rbtree through rb_erase(), but not set the node to EMPTY, which may result in uaf access. We should use RB_CLEAR_NODE() set the erased node to EMPTY, then pde_subdir_next() will return NULL to avoid uaf access. We found an uaf issue while using stress-ng testing, need to run testcase getdent and tun in the same time. The steps of the issue is as follows: 1) use getdent to traverse dir /proc/pid/net/dev_snmp6/, and current pde is tun3; 2) in the [time windows] unregister netdevice tun3 and tun2, and erase them from rbtree. erase tun3 first, and then erase tun2. the pde(tun2) will be released to slab; 3) continue to getdent process, then pde_subdir_next() will return pde(tun2) which is released, it will case uaf access. CPU 0 | CPU 1 ------------------------------------------------------------------------- traverse dir /proc/pid/net/dev_snmp6/ | unregister_netdevice(tun->dev) //tun3 tun2 sys_getdents64() | iterate_dir() | proc_readdir() | proc_readdir_de() | snmp6_unregister_dev() pde_get(de); | proc_remove() read_unlock(&proc_subdir_lock); | remove_proc_subtree() | write_lock(&proc_subdir_lock); [time window] | rb_erase(&root->subdir_node, &parent->subdir); | write_unlock(&proc_subdir_lock); read_lock(&proc_subdir_lock); | next = pde_subdir_next(de); | pde_put(de); | de = next; //UAF | rbtree of dev_snmp6 | pde(tun3) / \ NULL pde(tun2) |
Risk And Classification
EPSS: 0.037520000 probability, percentile 0.882530000 (date 2026-06-08)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected 710585d4922fd315f2cada8fbe550ae8ed23e994 1d1596d68a6f11d28f677eedf6cf5b17dbfeb491 git | Not specified |
| CNA | Linux | Linux | affected 710585d4922fd315f2cada8fbe550ae8ed23e994 c81d0385500446efe48c305bbb83d47f2ae23a50 git | Not specified |
| CNA | Linux | Linux | affected 710585d4922fd315f2cada8fbe550ae8ed23e994 4cba73c4c89219beef7685a47374bf88b1022369 git | Not specified |
| CNA | Linux | Linux | affected 710585d4922fd315f2cada8fbe550ae8ed23e994 6f2482745e510ae1dacc9b090194b9c5f918d774 git | Not specified |
| CNA | Linux | Linux | affected 710585d4922fd315f2cada8fbe550ae8ed23e994 67272c11f379d9aa5e0f6b16286b9d89b3f76046 git | Not specified |
| CNA | Linux | Linux | affected 710585d4922fd315f2cada8fbe550ae8ed23e994 623bb26127fb581a741e880e1e1a47d79aecb6f8 git | Not specified |
| CNA | Linux | Linux | affected 710585d4922fd315f2cada8fbe550ae8ed23e994 03de7ff197a3d0e17d0d5c58fdac99a63cba8110 git | Not specified |
| CNA | Linux | Linux | affected 710585d4922fd315f2cada8fbe550ae8ed23e994 895b4c0c79b092d732544011c3cecaf7322c36a1 git | Not specified |
| CNA | Linux | Linux | affected 3.19 | Not specified |
| CNA | Linux | Linux | unaffected 3.19 semver | Not specified |
| CNA | Linux | Linux | unaffected 5.4.302 5.4.* semver | Not specified |
| CNA | Linux | Linux | unaffected 5.10.247 5.10.* semver | Not specified |
| CNA | Linux | Linux | unaffected 5.15.197 5.15.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.1.159 6.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.6.117 6.6.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.59 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.17.9 6.17.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18 * original_commit_for_fix | Not specified |
| ADP | Siemens | RUGGEDCOM RST2428P | affected V4.0 custom | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/1d1596d68a6f11d28f677eedf6cf5b17dbfeb491 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/4cba73c4c89219beef7685a47374bf88b1022369 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/67272c11f379d9aa5e0f6b16286b9d89b3f76046 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/895b4c0c79b092d732544011c3cecaf7322c36a1 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/623bb26127fb581a741e880e1e1a47d79aecb6f8 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/c81d0385500446efe48c305bbb83d47f2ae23a50 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| cert-portal.siemens.com/productcert/html/ssa-253495.html | 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e | cert-portal.siemens.com | |
| git.kernel.org/stable/c/6f2482745e510ae1dacc9b090194b9c5f918d774 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/03de7ff197a3d0e17d0d5c58fdac99a63cba8110 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.