CVE-2024-49870

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

cachefiles: fix dentry leak in cachefiles_open_file()

A dentry leak may be caused when a lookup cookie and a cull are concurrent:

P1 | P2

-----------------------------------------------------------

cachefiles_lookup_cookie

cachefiles_look_up_object

lookup_one_positive_unlocked

// get dentry

cachefiles_cull

inode->i_flags |= S_KERNEL_FILE;

cachefiles_open_file

cachefiles_mark_inode_in_use

__cachefiles_mark_inode_in_use

can_use = false

if (!(inode->i_flags & S_KERNEL_FILE))

can_use = true

return false

return false

// Returns an error but doesn't put dentry

After that the following WARNING will be triggered when the backend folder

is umounted:

==================================================================

BUG: Dentry 000000008ad87947{i=7a,n=D

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References