xen: fix UAF in dmabuf_exp_from_pages()
Affects Linux kernel builds with the Xen gntdev dma-buf export code path, from 4.19.0 up to the fixed releases 6.6.160, 6.12.42, 6.15.10 and 6.16.1 on their branches.
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Fix
- Fixed in 6.6.160, 6.12.42, 6.15.10, 6.16.1
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
In the Linux kernel, the following vulnerability has been resolved: xen: fix UAF in dmabuf_exp_from_pages() [dma_buf_fd() fixes; no preferences regarding the tree it goes through - up to xen folks] As soon as we'd inserted a file reference into descriptor table, another thread could close it. That's fine for the case when all we are doing is returning that descriptor to userland (it's a race, but it's a userland race and there's nothing the kernel can do about it). However, if we follow fd_install() with any kind of access to objects that would be destroyed on close (be it the struct file itself or anything destroyed by its ->release()), we have a UAF. dma_buf_fd() is a combination of reserving a descriptor and fd_install(). gntdev dmabuf_exp_from_pages() calls it and then proceeds to access the objects destroyed on close - starting with gntdev_dmabuf itself. Fix that by doing reserving descriptor before anything else and do fd_install() only when everything had been set up.
Timeline
- CVE published
- Record last updated
Affected versions
- Linux Linux
Version range not reported
- Linux Linux
4.19
- KernelLinux
From 4.19.0 · fixed in 6.6.160; From 6.7.0 · fixed in 6.12.42; From 6.13.0 · fixed in 6.15.10; From 6.16.0 · fixed in 6.16.1
References 6
git.kernel.org
Questions about CVE-2025-38595
What does this mean?
After a file descriptor is installed, another thread can close it and destroy objects such as gntdev_dmabuf that the kernel still uses. This use-after-free can corrupt kernel memory.Source: git.kernel.org
Am I affected, and how do I check?
The bug is in the Xen gntdev dma-buf export code (dmabuf_exp_from_pages in drivers/xen/gntdev-dmabuf.c). The listed Linux kernel ranges are 4.19.0 to before 6.6.160, 6.7.0 to before 6.12.42, 6.13.0 to before 6.15.10, and 6.16.0 only, so check your kernel version with uname -r against those ranges.Source: git.kernel.org
What should I do about it?
Upgrade to the fixed release for your branch: 6.6.160, 6.12.42, 6.15.10, or 6.16.1.Source: git.kernel.org
Is it being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data