CVE-2026-64205: Linux Kernel

Medium severity, CVSS 5.5. EPSS: 0.1% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: i2c: i801: fix hardware state machine corruption in error path A severe livelock and subsequent Hung Task panic were observed in the i2c-i801 driver during concurrent Fuzzing. The crash is caused by an unconditional hardware register cleanup in the error handling path of i801_access(). When i801_check_pre() fails (e.g., returning -EBUSY because the SMBus controller is actively used by BIOS/ACPI), the kernel does not actually acquire the hardware ownership. However, the code jumps to the 'out' label and executes: iowrite8(SMBHSTSTS_INUSE_STS | STATUS_FLAGS, SMBHSTSTS(priv)); This forcefully clears the INUSE_STS lock and resets the hardware status flags without owning the controller. Doing so interrupts ongoing BIOS/ACPI transactions and totally corrupts the SMBus hardware state machine. Consequently, all subsequent i801_access() calls fail at the pre-check stage, triggering an endless stream of "SMBus is busy, can't use it!" error logs. Over a slow serial console, this printk flood monopolizes the CPU (Console Livelock), starving other processes trying to acquire the mmap_lock down_read semaphore, ultimately triggering the hung task watchdog. Fix this by moving the 'out' label below the hardware register cleanup. If i801_check_pre() fails, we safely bypass the iowrite8() and only release the software locks (pm_runtime and mutex), strictly adhering to the rule of not releasing resources that were never acquired.

Affected products

• Linux Linux Kernel: from 6.3, before 6.6.148 (fixed in 6.6.148); from 6.7, before 6.12.101 (fixed in 6.12.101); from 6.13, before 6.18.39 (fixed in 6.18.39); from 6.19, before 7.1.4 (fixed in 7.1.4)

Published 2026-07-20. Last modified 2026-08-17.