CVE-2024-46742 in Linux
Summary
by MITRE • 09/18/2024
In the Linux kernel, the following vulnerability has been resolved:
smb/server: fix potential null-ptr-deref of lease_ctx_info in smb2_open()
null-ptr-deref will occur when (req_op_level == SMB2_OPLOCK_LEVEL_LEASE) and parse_lease_state() return NULL.
Fix this by check if 'lease_ctx_info' is NULL.
Additionally, remove the redundant parentheses in parse_durable_handle_context().
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 04/05/2026
The vulnerability identified as CVE-2024-46742 resides within the Linux kernel's Server Message Block implementation, specifically affecting the smb2_open() function in the SMB server subsystem. This issue represents a classic null pointer dereference condition that could potentially lead to system instability or denial of service. The vulnerability manifests when processing SMB2 operations with lease-level oplocks, creating a scenario where the kernel attempts to dereference a null pointer that should have been validated for existence prior to access. The flaw occurs during the parsing of lease state information within the SMB2 protocol handling mechanism, where the kernel fails to properly validate the lease context information pointer before attempting to access its contents. This type of vulnerability falls under the category of improper null pointer validation as defined by CWE-476, which specifically addresses null pointer dereference conditions that can lead to system crashes or potential privilege escalation scenarios.
The technical execution of this vulnerability requires a specific sequence of conditions to be met, including the presence of an SMB2 operation level set to SMB2_OPLOCK_LEVEL_LEASE and the subsequent failure of the parse_lease_state() function to return valid lease context information. When these conditions align, the parse_lease_state() function returns NULL, but the calling smb2_open() function does not properly check for this null return value before attempting to access the lease_ctx_info structure. This creates a direct path for a null pointer dereference that can result in kernel panic or system crash, effectively rendering the SMB server service unavailable to legitimate users. The vulnerability demonstrates a clear violation of proper defensive programming practices where input validation and pointer checking mechanisms are insufficiently implemented. According to ATT&CK framework category T1499, this vulnerability could be exploited to achieve system disruption and denial of service, making it particularly concerning for enterprise environments where SMB services are heavily utilized for file sharing and network resource access.
The operational impact of CVE-2024-46742 extends beyond simple system instability, as it represents a potential vector for persistent service disruption within networked environments that rely on SMB protocols for critical operations. Organizations running Linux systems with SMB server functionality may experience unexpected service interruptions, particularly in environments where automated file sharing operations or remote desktop services depend on SMB2 protocol handling. The vulnerability affects systems that process SMB2 lease operations, which are commonly used in enterprise file servers, virtual desktop infrastructures, and cloud storage solutions. The fix implemented addresses this by introducing proper null pointer validation before accessing the lease_ctx_info structure, ensuring that the code path gracefully handles cases where lease context information cannot be parsed successfully. Additionally, the fix includes removal of redundant parentheses in the parse_durable_handle_context() function, which while not directly related to the null pointer issue, represents good code hygiene and improves overall code maintainability and readability. The mitigation approach aligns with standard security practices for preventing null pointer dereference vulnerabilities and follows the principle of least privilege by ensuring proper input validation at the point of use. This vulnerability highlights the importance of robust error handling in kernel space code and demonstrates how seemingly minor validation gaps can lead to significant operational impacts in enterprise network services.
The remediation of CVE-2024-46742 requires deployment of updated kernel versions that include the specific fix for null pointer validation in the smb2_open() function. System administrators should prioritize patching affected systems, particularly those hosting SMB servers or file sharing services that may be exposed to external network traffic. The fix operates at the kernel level and requires a system reboot to take effect, making coordinated patch management essential for maintaining service availability. Organizations should conduct thorough testing of patched systems to ensure that the SMB server functionality remains operational and that no regressions have been introduced by the fix. Security monitoring should be enhanced to detect potential exploitation attempts targeting this vulnerability, particularly in environments where SMB services are exposed to untrusted networks or where the vulnerability could be leveraged as part of a broader attack chain. The vulnerability resolution demonstrates the importance of continuous security auditing of kernel code and the necessity of maintaining up-to-date security patches to protect against known exploitation vectors. This case study reinforces the critical role of kernel security in enterprise environments and the need for proactive vulnerability management strategies that include regular kernel updates and security assessments.