CVE-2025-40271

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 nodeto 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 toavoid uaf access.We found an uaf issue while using stress-ng testing, need to run testcasegetdent 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 tun2sys_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 Information

Associated Vulnerability

Patch Details

References

https://nvd.nist.gov/vuln/detail/CVE-2023-1234
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-1234