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How the CVE Works
A flaw exists in the Linux kernel’s FS DAX (Direct Access) subsystem within the `wait_entry_unlocked_exclusive()` function. This function is designed to wait for a locked entry in the XArray to become unlocked without advancing the iterator. To wait, it must drop the XArray lock, which requires calling xas_pause(). However, `xas_pause()` has the side-effect of advancing the iterator to the next index. On the next loop iteration, the caller reloads the entry using this now-advanced iterator state, inadvertently skipping the original entry that was being processed. This race condition can lead to a use-after-free or other corruption when the skipped entry is a truncated page, triggering a kernel warning and potential system crash, as observed in generic/068 xfstests.
DailyCVE Form
Platform: Linux Kernel
Version: Up to 6.15.0-rc7
Vulnerability: Race Condition
Severity: High
Date: 2025-07-10
Prediction: 2025-08-15
What Undercode Say:
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Reproduce the issue with xfstests git clone git://git.kernel.org/pub/scm/fs/xfs/xfstests-dev.git cd xfstests-dev ./check generic/068 Kernel log showing the warning dmesg | grep "WARNING:truncate_folio_batch_exceptionals" Check kernel version uname -r
How Exploit:
A local attacker could potentially exploit this race condition by repeatedly triggering filesystem operations, such as truncating a file on a FS DAX-enabled volume, while it is being actively scanned. This could lead to a kernel crash (Denial of Service) or potentially allow for arbitrary code execution in the kernel context.
Protection from this CVE
Apply kernel patch.
Update kernel.
Disable FS DAX.
Impact:
Kernel panic.
Denial of Service.
Potential privilege escalation.
🎯Let’s Practice Exploiting & Learn Patching For Free:
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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