CVE-2016-6327 in Linux
Summary
by MITRE
drivers/infiniband/ulp/srpt/ib_srpt.c in the Linux kernel before 4.5.1 allows local users to cause a denial of service (NULL pointer dereference and system crash) by using an ABORT_TASK command to abort a device write operation.
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Analysis
by VulDB Data Team • 09/26/2022
The vulnerability described in CVE-2016-6327 resides within the Linux kernel's InfiniBand storage protocol target implementation, specifically in the srpt driver component that handles SCSI Remote Protocol operations. This flaw affects systems running Linux kernel versions prior to 4.5.1 and represents a critical denial of service vulnerability that can be exploited locally by users with minimal privileges. The vulnerability manifests through improper handling of ABORT_TASK commands within the InfiniBand storage subsystem, which is designed to manage storage operations over high-speed InfiniBand networks commonly used in data center environments.
The technical root cause of this vulnerability stems from a NULL pointer dereference condition that occurs when the ib_srpt.c driver processes an ABORT_TASK command during device write operations. When a local user submits such a command to abort an ongoing write operation, the driver fails to properly validate the target pointer before attempting to dereference it, leading to a kernel panic and system crash. This represents a classic CWE-476 NULL Pointer Dereference vulnerability that demonstrates poor input validation and error handling within kernel space code. The flaw exists specifically in the storage protocol target layer that manages SCSI operations over InfiniBand connections, making it particularly dangerous in environments where storage operations are frequent and critical.
The operational impact of this vulnerability extends beyond simple system crashes, as it can be exploited to disrupt critical storage operations in data center environments where InfiniBand networks are deployed. Local attackers can repeatedly trigger this condition to cause sustained denial of service, potentially affecting storage availability for legitimate users and applications. The vulnerability affects systems using InfiniBand storage protocols such as iSCSI over InfiniBand or other storage networking implementations that rely on the srpt driver. This creates a significant risk for enterprise environments where storage reliability is paramount, as the system crash can result in data loss, service interruption, and potential business impact. The vulnerability aligns with ATT&CK technique T1499.004 for Network Denial of Service and demonstrates how kernel-level flaws can be leveraged for system-wide disruption.
Mitigation strategies for this vulnerability primarily involve upgrading to Linux kernel version 4.5.1 or later, where the NULL pointer dereference has been addressed through proper input validation and pointer checking mechanisms. System administrators should also implement monitoring solutions to detect unusual patterns of ABORT_TASK command usage that might indicate exploitation attempts. Additional defensive measures include restricting local user privileges where possible, implementing proper access controls for InfiniBand storage interfaces, and maintaining regular kernel update schedules to address known vulnerabilities. The fix implemented in kernel 4.5.1 demonstrates proper error handling practices that validate pointers before dereferencing and implement graceful degradation rather than system crashes. Organizations using InfiniBand storage solutions should conduct vulnerability assessments to identify systems running affected kernel versions and prioritize patching efforts accordingly.