CVE-2023-54313
Unknown Unknown - Not Provided

Null Pointer Dereference in Linux Kernel OverlayFS ACL Handling

Publication date: 2025-12-30

Last updated on: 2025-12-30

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: ovl: fix null pointer dereference in ovl_get_acl_rcu() Following process: P1 P2 path_openat link_path_walk may_lookup inode_permission(rcu) ovl_permission acl_permission_check check_acl get_cached_acl_rcu ovl_get_inode_acl realinode = ovl_inode_real(ovl_inode) drop_cache __dentry_kill(ovl_dentry) iput(ovl_inode) ovl_destroy_inode(ovl_inode) dput(oi->__upperdentry) dentry_kill(upperdentry) dentry_unlink_inode upperdentry->d_inode = NULL ovl_inode_upper upperdentry = ovl_i_dentry_upper(ovl_inode) d_inode(upperdentry) // returns NULL IS_POSIXACL(realinode) // NULL pointer dereference , will trigger an null pointer dereference at realinode: [ 205.472797] BUG: kernel NULL pointer dereference, address: 0000000000000028 [ 205.476701] CPU: 2 PID: 2713 Comm: ls Not tainted 6.3.0-12064-g2edfa098e750-dirty #1216 [ 205.478754] RIP: 0010:do_ovl_get_acl+0x5d/0x300 [ 205.489584] Call Trace: [ 205.489812] <TASK> [ 205.490014] ovl_get_inode_acl+0x26/0x30 [ 205.490466] get_cached_acl_rcu+0x61/0xa0 [ 205.490908] generic_permission+0x1bf/0x4e0 [ 205.491447] ovl_permission+0x79/0x1b0 [ 205.491917] inode_permission+0x15e/0x2c0 [ 205.492425] link_path_walk+0x115/0x550 [ 205.493311] path_lookupat.isra.0+0xb2/0x200 [ 205.493803] filename_lookup+0xda/0x240 [ 205.495747] vfs_fstatat+0x7b/0xb0 Fetch a reproducer in [Link]. Use the helper ovl_i_path_realinode() to get realinode and then do non-nullptr checking.

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Meta Information

Published
2025-12-30
Last Modified
2025-12-30
Generated
2026-07-06
AI Q&A
2025-12-30
EPSS Evaluated
2026-07-05
NVD
CVE-2023-54313
EUVD
EUVD-2023-60491

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel 6.3.0

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability is a null pointer dereference in the Linux kernel's overlay filesystem (ovl) component, specifically in the function ovl_get_acl_rcu(). It occurs when the code attempts to access a POSIX ACL (Access Control List) on a real inode that has been set to NULL, leading to a kernel crash (BUG). This happens during permission checks in the overlay filesystem, causing the kernel to dereference a NULL pointer and potentially crash or behave unexpectedly.

Impact Analysis

This vulnerability can cause the Linux kernel to crash due to a NULL pointer dereference when accessing certain filesystem permissions in the overlay filesystem. This can lead to denial of service (system instability or crashes) on affected systems, potentially disrupting normal operations.

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