Cloudanix VulnDB

CVE-2025-40271

None

CVSS

—

EPSS

0.5%

Published

Dec 6, 2025

CISA due date

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The record

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 packages

Ecosystem Package Introduced Fixed
Linux Kernel 0 5.4.302
Linux Kernel 3.19.0 5.4.302
Mageia:9 kernel 0 6.6.120-1.mga9
Mageia:9 kernel-linus 0 6.6.120-1.mga9
Mageia:9 kmod-virtualbox 0 7.1.14-14.mga9
Mageia:9 kmod-xtables-addons 0 3.24-88.mga9
openSUSE:Leap 16.0 dtb-aarch64 0 6.12.0-160000.9.1
openSUSE:Leap 16.0 kernel-64kb 0 6.12.0-160000.9.1
openSUSE:Leap 16.0 kernel-azure 0 6.12.0-160000.9.1
openSUSE:Leap 16.0 kernel-default 0 6.12.0-160000.9.1
openSUSE:Leap 16.0 kernel-default-base 0 6.12.0-160000.9.1.160000.2.6
openSUSE:Leap 16.0 kernel-docs 0 6.12.0-160000.9.1
openSUSE:Leap 16.0 kernel-kvmsmall 0 6.12.0-160000.9.1
openSUSE:Leap 16.0 kernel-obs-build 0 6.12.0-160000.9.1
openSUSE:Leap 16.0 kernel-obs-qa 0 6.12.0-160000.9.1
openSUSE:Leap 16.0 kernel-rt 0 6.12.0-160000.9.1
openSUSE:Leap 16.0 kernel-source 0 6.12.0-160000.9.1
openSUSE:Leap 16.0 kernel-syms 0 6.12.0-160000.9.1
openSUSE:Leap 16.0 kernel-zfcpdump 0 6.12.0-160000.9.1

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