CVE-2026-23161
Unknown Unknown - Not Provided
Race Condition in Linux Kernel shmem Swap Causes Data Corruption

Publication date: 2026-02-14

Last updated on: 2026-04-03

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: mm/shmem, swap: fix race of truncate and swap entry split The helper for shmem swap freeing is not handling the order of swap entries correctly. It uses xa_cmpxchg_irq to erase the swap entry, but it gets the entry order before that using xa_get_order without lock protection, and it may get an outdated order value if the entry is split or changed in other ways after the xa_get_order and before the xa_cmpxchg_irq. And besides, the order could grow and be larger than expected, and cause truncation to erase data beyond the end border. For example, if the target entry and following entries are swapped in or freed, then a large folio was added in place and swapped out, using the same entry, the xa_cmpxchg_irq will still succeed, it's very unlikely to happen though. To fix that, open code the Xarray cmpxchg and put the order retrieval and value checking in the same critical section. Also, ensure the order won't exceed the end border, skip it if the entry goes across the border. Skipping large swap entries crosses the end border is safe here. Shmem truncate iterates the range twice, in the first iteration, find_lock_entries already filtered such entries, and shmem will swapin the entries that cross the end border and partially truncate the folio (split the folio or at least zero part of it). So in the second loop here, if we see a swap entry that crosses the end order, it must at least have its content erased already. I observed random swapoff hangs and kernel panics when stress testing ZSWAP with shmem. After applying this patch, all problems are gone.
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Meta Information
Published
2026-02-14
Last Modified
2026-04-03
Generated
2026-05-27
AI Q&A
2026-02-14
EPSS Evaluated
2026-05-25
NVD
CVE-2026-23161
EUVD
EUVD-2026-5877
Affected Vendors & Products
Showing 9 associated CPEs
Vendor Product Version / Range
linux linux_kernel 6.19
linux linux_kernel 6.19
linux linux_kernel 6.19
linux linux_kernel 6.19
linux linux_kernel 6.19
linux linux_kernel 6.19
linux linux_kernel 6.19
linux linux_kernel From 6.13 (inc) to 6.18.9 (exc)
linux linux_kernel From 6.12 (inc) to 6.12.69 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-362 The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability exists in the Linux kernel's memory management subsystem, specifically in the handling of shared memory (shmem) swap entries. The issue arises because the helper function that frees shmem swap entries does not correctly handle the order of these entries. It retrieves the order of a swap entry without proper locking, which can lead to using outdated order values if the entry is split or changed concurrently.

Additionally, the order value can grow larger than expected, potentially causing truncation operations to erase data beyond the intended boundary. This can happen if swap entries are swapped in or freed and then replaced by a large memory folio that is swapped out using the same entry.

The fix involves combining the retrieval of the order and the value checking into a single critical section to prevent race conditions, and ensuring that entries crossing the end boundary are skipped safely to avoid data corruption.


How can this vulnerability impact me? :

This vulnerability can lead to data corruption or loss due to improper handling of swap entries in shared memory. Specifically, truncation operations might erase data beyond the intended boundaries, potentially affecting system stability and data integrity.

In practical terms, this could cause random system hangs or kernel panics, especially under stress conditions involving memory swapping (such as with ZSWAP and shmem). This instability can disrupt normal system operations and may result in loss of unsaved data.


How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:

I don't know


How can this vulnerability be detected on my network or system? Can you suggest some commands?

I don't know


What immediate steps should I take to mitigate this vulnerability?

I don't know


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