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CVE PROGRAM SOURCE RECORD7.8 High

CVE-2025-40271

fs/proc: fix uaf in proc_readdir_de()

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Status
Published
Published
Updated
Assigning organization
Linux

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)

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 710585d4922fd315f2cada8fbe550ae8ed23e994 to < 1d1596d68a6f11d28f677eedf6cf5b17dbfeb491affected
  • 710585d4922fd315f2cada8fbe550ae8ed23e994 to < c81d0385500446efe48c305bbb83d47f2ae23a50affected
  • 710585d4922fd315f2cada8fbe550ae8ed23e994 to < 4cba73c4c89219beef7685a47374bf88b1022369affected
  • 710585d4922fd315f2cada8fbe550ae8ed23e994 to < 6f2482745e510ae1dacc9b090194b9c5f918d774affected
  • 710585d4922fd315f2cada8fbe550ae8ed23e994 to < 67272c11f379d9aa5e0f6b16286b9d89b3f76046affected
  • 710585d4922fd315f2cada8fbe550ae8ed23e994 to < 623bb26127fb581a741e880e1e1a47d79aecb6f8affected
  • 710585d4922fd315f2cada8fbe550ae8ed23e994 to < 03de7ff197a3d0e17d0d5c58fdac99a63cba8110affected
  • 710585d4922fd315f2cada8fbe550ae8ed23e994 to < 895b4c0c79b092d732544011c3cecaf7322c36a1affected

Linux Linux

Default version status: affected

  • 3.19affected
  • 0 to < 3.19unaffected
  • 5.4.302 to ≤ 5.4.*unaffected
  • 5.10.247 to ≤ 5.10.*unaffected
  • 5.15.197 to ≤ 5.15.*unaffected
  • 6.1.159 to ≤ 6.1.*unaffected
  • 6.6.117 to ≤ 6.6.*unaffected
  • 6.12.59 to ≤ 6.12.*unaffected
  • 6.17.9 to ≤ 6.17.*unaffected
  • 6.18 to ≤ *unaffected

References