CVE-2026-74375 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
md/raid1,raid10: fix deadlock in read error recovery path
raid1d and raid10d may resubmit a split md cloned bio while handling a read error. In this case, resubmitting the bio can lead to a deadlock if the array is suspended before md_handle_request() acquires an active_io reference via percpu_ref_tryget_live().
Since the cloned bio already holds an active_io reference, trying to acquire another reference via percpu_ref_tryget_live() can lead to a deadlock while the array is suspended.
Fix this by using percpu_ref_get() for md cloned bios.
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Analysis
by VulDB Data Team • 08/15/2026
The vulnerability exists within the Linux kernel's software RAID implementation, specifically affecting md/raid1 and md/raid10 subsystems. This issue manifests as a deadlock condition during read error recovery operations when the system attempts to resubmit split md cloned bio structures. The problem occurs in the context of RAID array management where the kernel must handle failed read operations while maintaining data integrity across redundant storage arrays. When a read error occurs, the system attempts to resubmit the bio structure through the md_handle_request() function, but this process encounters a critical synchronization issue that can halt system operations.
The technical flaw stems from improper reference counting mechanisms within the percpu_ref subsystem. During read error recovery, the md/raid1 and md/raid10 daemons may need to resubmit cloned bio structures that already hold an active_io reference. When the array is suspended during this process, subsequent attempts to acquire another reference using percpu_ref_tryget_live() fail because the function returns false when the reference counter is in a state where it cannot be safely incremented. This creates a circular dependency where the system waits indefinitely for a resource that cannot be acquired due to the suspension state, resulting in complete system deadlock.
The operational impact of this vulnerability extends beyond simple system hangs to encompass potential data loss scenarios and complete system unresponsiveness during critical RAID operations. When a RAID array is suspended, typically during maintenance operations or when handling multiple concurrent errors, the deadlock condition can prevent any further I/O processing until manual intervention occurs. This affects enterprise storage systems where uninterrupted operation is critical, potentially leading to extended downtime for services relying on RAID configurations. The vulnerability particularly impacts systems using mdadm software RAID implementations where read error recovery is frequently triggered during normal operations or hardware degradation events.
The fix implemented addresses the core reference counting issue by changing the acquisition mechanism from percpu_ref_tryget_live() to percpu_ref_get() specifically for md cloned bios. This modification ensures that when a cloned bio structure needs to acquire an additional reference, it will block until the reference can be safely obtained rather than failing immediately and creating deadlock conditions. The solution aligns with established best practices for reference counting in concurrent systems and follows the principle of resource acquisition ordering to prevent circular dependencies. This remediation maintains system stability while preserving the integrity of RAID error recovery operations.
This vulnerability maps to CWE-362 (Concurrent Execution using Shared Resource with Unprotected Read-Write Access) and CWE-121 (Stack-based Buffer Overflow), as it involves improper synchronization of shared resources during concurrent operations. The issue can be categorized under ATT&CK technique T1490 (Inhibit System Recovery) as it prevents normal system recovery operations by creating deadlock conditions. The fix demonstrates proper implementation of reference counting patterns that prevent race conditions, aligning with security best practices for kernel-level resource management and concurrent programming. This vulnerability highlights the critical importance of careful synchronization in storage subsystems where system availability directly impacts business continuity and data protection requirements.