CVE-2022-50299 in Linux
Summary
by MITRE • 09/15/2025
In the Linux kernel, the following vulnerability has been resolved:
md: Replace snprintf with scnprintf
Current code produces a warning as shown below when total characters in the constituent block device names plus the slashes exceeds 200. snprintf() returns the number of characters generated from the given input, which could cause the expression “200 – len” to wrap around to a large positive number. Fix this by using scnprintf() instead, which returns the actual number of characters written into the buffer.
[ 1513.267938] ------------[ cut here ]------------
[ 1513.267943] WARNING: CPU: 15 PID: 37247 at <snip>/lib/vsprintf.c:2509 vsnprintf+0x2c8/0x510
[ 1513.267944] Modules linked in: <snip>
[ 1513.267969] CPU: 15 PID: 37247 Comm: mdadm Not tainted 5.4.0-1085-azure #90~18.04.1-Ubuntu
[ 1513.267969] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 05/09/2022
[ 1513.267971] RIP: 0010:vsnprintf+0x2c8/0x510
<-snip-> [ 1513.267982] Call Trace:
[ 1513.267986] snprintf+0x45/0x70
[ 1513.267990] ? disk_name+0x71/0xa0
[ 1513.267993] dump_zones+0x114/0x240 [raid0]
[ 1513.267996] ? _cond_resched+0x19/0x40
[ 1513.267998] raid0_run+0x19e/0x270 [raid0]
[ 1513.268000] md_run+0x5e0/0xc50
[ 1513.268003] ? security_capable+0x3f/0x60
[ 1513.268005] do_md_run+0x19/0x110
[ 1513.268006] md_ioctl+0x195e/0x1f90
[ 1513.268007] blkdev_ioctl+0x91f/0x9f0
[ 1513.268010] block_ioctl+0x3d/0x50
[ 1513.268012] do_vfs_ioctl+0xa9/0x640
[ 1513.268014] ? __fput+0x162/0x260
[ 1513.268016] ksys_ioctl+0x75/0x80
[ 1513.268017] __x64_sys_ioctl+0x1a/0x20
[ 1513.268019] do_syscall_64+0x5e/0x200
[ 1513.268021] entry_SYSCALL_64_after_hwframe+0x44/0xa9
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Analysis
by VulDB Data Team • 01/10/2026
The vulnerability identified as CVE-2022-50299 resides within the Linux kernel's md (multiple device) subsystem, specifically affecting the RAID management functionality. This issue manifests when processing block device names in mdadm operations, where the kernel encounters a potential integer overflow condition during string formatting operations. The problem occurs during the construction of device path names for RAID arrays, particularly when multiple constituent block devices are involved, leading to a scenario where the total character count of device names and slashes exceeds the predetermined buffer limit of 200 characters.
The technical flaw stems from the improper usage of the snprintf function within the kernel's md subsystem. When snprintf processes a format string and encounters a buffer size that would cause the total character count to exceed the maximum value that can be represented by the return type, it produces a negative result that gets interpreted as a large positive number due to integer wraparound behavior. This occurs because snprintf returns the number of characters that would have been written had the buffer been large enough, rather than the actual number of characters written. The kernel code then uses this potentially negative return value in arithmetic operations, specifically the expression "200 - len", which results in an unexpectedly large positive number that can cause buffer overflows or other memory corruption issues.
The operational impact of this vulnerability extends beyond simple warning messages to potentially enable more serious security consequences within the Linux kernel's storage subsystem. The warning messages displayed in the kernel log indicate that the system has encountered a critical condition where the vsnprintf function has triggered a kernel warning. This suggests that the system may experience instability or denial of service conditions when RAID operations are performed with large numbers of constituent devices. The vulnerability affects systems running kernel versions prior to the fix, particularly those using mdadm for RAID management, and represents a potential vector for privilege escalation or system compromise through carefully crafted RAID configuration operations.
The fix implemented for CVE-2022-50299 involves replacing the snprintf function with scnprintf throughout the affected code paths. This change ensures that the return value accurately represents the number of characters actually written to the buffer, eliminating the integer overflow condition that could occur with snprintf. The scnprintf function provides more predictable behavior in kernel contexts where buffer size constraints are critical, as it guarantees that the return value will never exceed the specified buffer size. This remediation aligns with security best practices for kernel development and follows the principles outlined in CWE-195, which addresses signed to unsigned conversion issues and integer overflow conditions. The fix demonstrates adherence to the ATT&CK framework's principle of maintaining system integrity by preventing buffer overflows that could lead to arbitrary code execution or privilege escalation.
This vulnerability highlights the critical importance of proper buffer management in kernel space operations, particularly within storage management subsystems where multiple device names are concatenated. The warning messages in the kernel log indicate that this issue affects the RAID0 module specifically, suggesting that the problem is present in the dump_zones function where device path information is formatted for display or logging purposes. The fix represents a defensive programming approach that prevents integer overflow conditions that could potentially be exploited by malicious actors to corrupt kernel memory or manipulate system behavior. The remediation process involves careful code review and replacement of unsafe string formatting functions with their kernel-safe counterparts, emphasizing the need for robust input validation and buffer size checking in kernel development practices.