CVE-2026-53030 Overview
CVE-2026-53030 is a memory leak vulnerability in the Linux kernel's Renesas I3C master driver. The flaw resides in the renesas_i3c_i3c_xfers() function within the i3c/master/renesas driver. The xfer structure allocated by renesas_i3c_alloc_xfer() was never freed before the function returned, causing kernel memory to leak on each transfer operation.
The upstream fix introduces the __free(kfree) cleanup attribute to automatically release the allocated memory when the variable goes out of scope. Repeated I3C transfers on affected systems progressively consume kernel memory, leading to potential resource exhaustion over time.
Critical Impact
Sustained I3C bus activity on systems using the Renesas I3C master driver can exhaust kernel memory, degrading system stability and enabling local denial-of-service conditions.
Affected Products
- Linux kernel versions containing the renesas_i3c_i3c_xfers() implementation in the I3C master driver
- Systems using Renesas I3C master controllers
- Stable kernel branches prior to the commits referenced in the patch series
Discovery Timeline
- 2026-06-24 - CVE CVE-2026-53030 published to NVD
- 2026-06-24 - Last updated in NVD database
Technical Details for CVE-2026-53030
Vulnerability Analysis
The vulnerability is a memory leak [CWE-401] in the Linux kernel's Inter-Integrated Circuit 3 (I3C) bus master driver for Renesas controllers. The function renesas_i3c_i3c_xfers() handles I3C transfer requests submitted to the master controller. During each invocation, the driver allocates an xfer structure through the helper renesas_i3c_alloc_xfer() to track the in-flight transfer.
The allocated structure was not released along any return path in renesas_i3c_i3c_xfers(). Each I3C transfer therefore leaks the memory occupied by the xfer structure. On systems performing frequent I3C bus operations, the cumulative leak reduces available kernel memory and can pressure the slab allocator.
The Exploit Prediction Scoring System (EPSS) currently rates this issue at a probability of 0.166%.
Root Cause
The root cause is missing deallocation logic. The driver allocates the xfer tracking structure but lacks a corresponding kfree() call before the function exits. Multiple return paths within the transfer handler compound the problem because each must independently release the allocation.
The upstream fix replaces manual lifetime management with the __free(kfree) scope-based cleanup attribute. This attribute, part of the kernel's modern resource management infrastructure, automatically invokes kfree() when the variable leaves its lexical scope, eliminating the leak on every return path.
Attack Vector
The vulnerability requires local access to a system using the Renesas I3C master driver. An attacker or buggy workload that can trigger repeated I3C transfers, whether through user-space interfaces exposed by the I3C subsystem or via attached I3C devices, can drive sustained allocation of the leaked structures. The vulnerability does not enable code execution or privilege escalation directly. It produces a denial-of-service condition through kernel memory exhaustion.
No verified proof-of-concept code is available. Refer to the Kernel Git Commit d7665c3 for the precise patch implementation.
Detection Methods for CVE-2026-53030
Indicators of Compromise
- Steady growth of the kernel slab cache associated with I3C xfer allocations on affected hardware
- Decreasing MemAvailable in /proc/meminfo correlated with sustained I3C bus activity
- kmemleak reports referencing renesas_i3c_alloc_xfer call stacks when kernel memory leak detection is enabled
Detection Strategies
- Enable CONFIG_DEBUG_KMEMLEAK on test systems and review /sys/kernel/debug/kmemleak for unreferenced allocations originating in the Renesas I3C driver
- Monitor slab statistics with slabtop for unbounded growth of kmalloc caches on systems performing frequent I3C transactions
- Track kernel version and confirm whether the patch commits 1b6a7e9, ab8f00f, or d7665c3 are present in the running build
Monitoring Recommendations
- Baseline kernel memory usage on systems using Renesas I3C controllers and alert on abnormal long-term growth
- Collect dmesg output for out-of-memory or slab allocation failure messages
- Forward host telemetry to a centralized analytics platform to correlate memory pressure with workload patterns over time
How to Mitigate CVE-2026-53030
Immediate Actions Required
- Identify systems running Linux kernels with the Renesas I3C master driver enabled (CONFIG_I3C_RENESAS or equivalent)
- Apply the stable kernel update containing commits 1b6a7e9, ab8f00f, or d7665c3 depending on the kernel branch in use
- Restart affected systems to load the patched kernel after deployment
Patch Information
The fix is available in the upstream Linux kernel through three commits across stable branches:
The patch applies the __free(kfree) cleanup attribute to the xfer variable in renesas_i3c_i3c_xfers(), ensuring automatic release on every return path.
Workarounds
- Where patching is not immediately feasible, restrict workloads that generate sustained I3C transfer activity on affected hardware
- Schedule periodic reboots on long-running systems to reclaim leaked kernel memory until the patched kernel is deployed
- Disable the Renesas I3C master driver if the controller is not required for system operation
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
