CVE-2026-72358 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
drm/xe/pt: prevent invalid cursor access for purged BOs
During a page table walk for binding, xe_pt_stage_bind() explicitly skips initializing the xe_res_cursor for purged BOs, treating them similarly to NULL VMAs by only setting the cursor size.
However, xe_pt_hugepte_possible() and xe_pt_scan_64K() did not check if the BO was purged before attempting to walk the cursor using xe_res_dma() and xe_res_next(). Because the cursor was left uninitialized for purged BOs, this falls through and triggers warnings like:
WARNING: drivers/gpu/drm/xe/xe_res_cursor.h:274 at xe_res_next
Fix this by explicitly checking if the BO is purged in both xe_pt_hugepte_possible() and xe_pt_scan_64K(), returning early just as we do for NULL VMAs, avoiding the invalid cursor accesses entirely.
As a precaution, also zero-initialize the cursor in xe_pt_stage_bind() to ensure we don't pass garbage data into the page table walkers if we ever hit a similar edge case in the future.
(cherry picked from commit 4c7b9c6ece32440e5a435a92076d049450cd2d2e)
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Analysis
by VulDB Data Team • 08/15/2026
This vulnerability exists within the intel graphics driver subsystem of the linux kernel specifically affecting the xe driver's page table management functionality. The issue stems from improper handling of purged buffer objects during page table binding operations, creating a potential for invalid memory access patterns that could lead to system instability or information disclosure. The flaw manifests when the kernel attempts to process page table entries for graphics buffer objects that have already been purged from memory, resulting in undefined behavior during cursor traversal operations.
The technical root cause involves inconsistent state management within the graphics driver's memory management subsystem. During page table binding operations, the xe_pt_stage_bind() function correctly identifies purged buffer objects and skips cursor initialization, treating them like NULL VMAs by only setting cursor size. However, subsequent functions xe_pt_hugepte_possible() and xe_pt_scan_64K() fail to perform this same validation check before attempting to traverse the cursor using xe_res_dma() and xe_res_next() functions. This inconsistency creates a scenario where uninitialized cursor data is accessed, leading to kernel warnings and potential memory corruption.
The operational impact of this vulnerability extends beyond simple warning messages to potentially compromise system stability during graphics-intensive operations. When purged buffer objects are processed through page table walkers, the invalid cursor access can trigger kernel panic conditions or cause denial of service scenarios in graphics applications. Attackers could potentially exploit this weakness to cause system crashes or in more sophisticated scenarios, manipulate memory layouts to achieve privilege escalation. The vulnerability particularly affects systems running the intel graphics driver with xe (xe_driver) and is classified under CWE-457 as use of uninitialized variable.
The mitigation strategy implemented addresses the core issue by adding explicit purge checks in both problematic functions, ensuring early return similar to how NULL VMAs are handled. This approach follows established security practices for preventing use-after-free conditions and invalid memory access patterns. Additionally, the code now includes zero-initialization of cursors during xe_pt_stage_bind() operations, providing defensive programming that prevents garbage data from being passed to page table walkers even if similar edge cases arise in future implementations.
This vulnerability aligns with ATT&CK technique T1068 by potentially enabling privilege escalation through kernel memory corruption, and T1499 by creating conditions for system instability and denial of service. The fix demonstrates proper defensive programming practices that should be applied across similar graphics driver components to prevent analogous issues in other subsystems. The solution maintains backward compatibility while strengthening the driver's resilience against malformed graphics buffer object states during page table management operations.