CVE-2024-49870: Linux kernel · cachefiles: fix dentry leak in cachefiles_open_file()
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 6.8.0-1023.25~22.04.1 : update Linux kernel when convenient.
Data as of 12 Nov 2026, 19:06 UTC
- Patch
- Available – fixed in 6.8.0-1023.25~22.04.1, 6.8.0-1025.30~22.04.1, 6.8.0-1024.26~22.04.1 +29
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 21 Oct 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 12 Nov 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Patches and advisories
- ubuntu.com/security/notices/USN-7276-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7277-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7301-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7303-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7304-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7303-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7310-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7311-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7303-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7384-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7385-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7386-1 (opens in a new tab)
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azure-nvidiapkg:deb/ubuntu/linux-azure-nvidia?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
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=Dx_1_1.img} still in use (1) [unmount of ext4 sda] WARNING: CPU: 4 PID: 359261 at fs/dcache.c:1767 umount_check+0x5d/0x70 CPU: 4 PID: 359261 Comm: umount Not tainted 6.6.0-dirty #25 RIP: 0010:umount_check+0x5d/0x70 Call Trace: <TASK> d_walk+0xda/0x2b0 do_one_tree+0x20/0x40 shrink_dcache_for_umount+0x2c/0x90 generic_shutdown_super+0x20/0x160 kill_block_super+0x1a/0x40 ext4_kill_sb+0x22/0x40 deactivate_locked_super+0x35/0x80 cleanup_mnt+0x104/0x160 ================================================================== Whether cachefiles_open_file() returns true or false, the reference count obtained by lookup_positive_unlocked() in cachefiles_look_up_object() should be released. Therefore release that reference count in cachefiles_look_up_object() to fix the above issue and simplify the code.
References
- ubuntu.com/security/CVE-2024-49870 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2024-49870 (opens in a new tab)
- git.kernel.org/linus/da6ef2dffe6056aad3435e6cf7c6471c2a62187c (opens in a new tab)
- git.kernel.org/stable/c/d32ff64c872d7e08e893c32ba6a2374583444410 (opens in a new tab)
- git.kernel.org/stable/c/c7d10fa7d7691558ff967668494672415f5fa151 (opens in a new tab)
- git.kernel.org/stable/c/e4a28489b310339b2b8187bec0a437709be551c1 (opens in a new tab)
- git.kernel.org/stable/c/7fa2382f97421978514a419c93054eca69f5247b (opens in a new tab)
- git.kernel.org/stable/c/da6ef2dffe6056aad3435e6cf7c6471c2a62187c (opens in a new tab)
- ubuntu.com/security/notices/USN-7276-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7277-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7301-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7303-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7304-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7303-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7310-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7311-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7303-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7384-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7385-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7386-1 (opens in a new tab)