CVE-2022-49376 in Linux
Summary
by MITRE • 02/26/2025
In the Linux kernel, the following vulnerability has been resolved:
scsi: sd: Fix potential NULL pointer dereference
If sd_probe() sees an early error before sdkp->device is initialized, sd_zbc_release_disk() is called. This causes a NULL pointer dereference when sd_is_zoned() is called inside that function. Avoid this by removing the call to sd_zbc_release_disk() in sd_probe() error path.
This change is safe and does not result in zone information memory leakage because the zone information for a zoned disk is allocated only when sd_revalidate_disk() is called, at which point sdkp->disk_dev is fully set, resulting in sd_disk_release() being called when needed to cleanup a disk zone information using sd_zbc_release_disk().
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Analysis
by VulDB Data Team • 06/12/2025
The vulnerability described in CVE-2022-49376 represents a critical NULL pointer dereference issue within the Linux kernel's SCSI subsystem, specifically affecting the sd (SCSI disk) driver component. This flaw exists in the device probing and initialization sequence where the kernel attempts to handle zoned block devices. The vulnerability manifests when the sd_probe() function encounters an early error condition before the sdkp->device structure has been properly initialized. During such error scenarios, the kernel incorrectly invokes sd_zbc_release_disk() function, which subsequently attempts to call sd_is_zoned() on a NULL pointer, leading to a kernel panic or system crash. This type of vulnerability falls under CWE-476 which specifically addresses NULL pointer dereference conditions that can lead to system instability and potential denial of service attacks.
The technical implementation of this flaw occurs within the SCSI disk driver's error handling path where the kernel's device initialization logic fails to properly account for the state of device structures during early error conditions. When sd_probe() encounters an error before sdkp->device is fully initialized, it proceeds to call sd_zbc_release_disk() which then attempts to access the sd_is_zoned() function without proper null checking. This creates an execution path where a NULL pointer dereference occurs, potentially allowing malicious actors to trigger system crashes or, in more sophisticated attack scenarios, potentially enabling privilege escalation or information disclosure. The vulnerability demonstrates poor error handling and resource management practices in kernel space code, where functions are called without verifying that required data structures have been properly initialized.
The operational impact of this vulnerability extends beyond simple system crashes to potentially affect enterprise storage environments where SCSI and zoned block devices are commonly deployed. Organizations running Linux systems with SCSI storage arrays or zoned devices face the risk of unexpected system downtime, especially during device initialization or error recovery scenarios. The vulnerability is particularly concerning in high-availability environments where system stability is critical, as a single device probe failure could potentially bring down entire storage subsystems. According to ATT&CK framework, this vulnerability could be leveraged as part of a broader attack chain where an adversary attempts to destabilize system resources or create conditions for more sophisticated exploitation techniques. The flaw also represents a potential denial of service vector that could be exploited by unauthenticated users or processes with limited privileges to disrupt normal system operations.
The fix implemented for CVE-2022-49376 addresses the root cause by removing the problematic call to sd_zbc_release_disk() from the sd_probe() error path, ensuring that the function is only invoked when the device structure is properly initialized. This solution maintains proper resource cleanup semantics while preventing the NULL pointer dereference condition. The patch correctly identifies that zone information for zoned disks is only allocated during the sd_revalidate_disk() call, where sdkp->disk_dev is fully initialized and sd_disk_release() is properly invoked to handle cleanup. This approach aligns with proper kernel development practices and follows the principle of defensive programming where functions are only called when preconditions are met. The fix is considered safe and does not introduce memory leaks since the zone information cleanup mechanism remains intact and is properly coordinated with the device lifecycle management. System administrators should prioritize applying this patch to all Linux systems running kernel versions affected by this vulnerability to maintain system stability and prevent potential exploitation by malicious actors.