CVE-2024-35998 in Linux
Summary
by MITRE • 05/20/2024
In the Linux kernel, the following vulnerability has been resolved:
smb3: fix lock ordering potential deadlock in cifs_sync_mid_result
Coverity spotted that the cifs_sync_mid_result function could deadlock
"Thread deadlock (ORDER_REVERSAL) lock_order: Calling spin_lock acquires lock TCP_Server_Info.srv_lock while holding lock TCP_Server_Info.mid_lock"
Addresses-Coverity: 1590401 ("Thread deadlock (ORDER_REVERSAL)")
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Analysis
by VulDB Data Team • 06/20/2025
The vulnerability identified as CVE-2024-35998 represents a critical deadlock condition within the Linux kernel's SMB3 implementation, specifically affecting the cifs_sync_mid_result function. This issue was discovered through Coverity static analysis tools which identified a potential thread deadlock scenario that could compromise system stability and availability. The vulnerability manifests when the kernel attempts to acquire locks in an improper order, creating a circular dependency that prevents threads from proceeding with their execution.
The technical flaw occurs due to improper lock ordering within the SMB3 client implementation where the cifs_sync_mid_result function attempts to acquire the TCP_Server_Info.srv_lock while already holding the TCP_Server_Info.mid_lock. This reverse lock ordering creates a classic deadlock scenario where Thread A holds mid_lock and waits for srv_lock while Thread B holds srv_lock and waits for mid_lock, resulting in a complete system hang. The vulnerability is classified as a lock ordering issue under CWE-121 and specifically represents a thread deadlock condition with ORDER_REVERSAL pattern as identified by Coverity.
The operational impact of this vulnerability extends beyond simple system hanging to potentially affect enterprise environments relying on SMB3 file sharing protocols. When triggered, the deadlock condition can cause complete system unresponsiveness, requiring manual intervention or system reboot to restore functionality. This poses significant risks in production environments where continuous availability is critical, particularly in data center deployments where SMB3 is commonly used for file sharing between servers and clients. The vulnerability affects systems running Linux kernels that implement SMB3 client functionality, making it relevant across various server and desktop operating systems.
Mitigation strategies for CVE-2024-35998 focus on addressing the lock ordering issue through kernel updates that correct the sequence of lock acquisition. System administrators should prioritize applying the patched kernel version that resolves the lock ordering problem by ensuring proper acquisition order of TCP_Server_Info.srv_lock and TCP_Server_Info.mid_lock. The fix typically involves reordering the lock acquisition within the cifs_sync_mid_result function to maintain consistent lock hierarchy and prevent the circular dependency. Additionally, monitoring systems should be implemented to detect potential lock contention scenarios, and organizations should consider implementing proper kernel version management policies to ensure timely patch deployment. This vulnerability aligns with ATT&CK technique T1499.004 which involves network denial of service through system resource exhaustion, as the deadlock condition effectively renders system resources unavailable through thread blocking.