CVE-2026-64135: Undefined Security Weakness

In the Linux kernel, the following vulnerability has been resolved:

hwmon: (pmbus/adm1266) widen blackbox-info buffer to I2C_SMBUS_BLOCK_MAX

adm1266_nvmem_read_blackbox() declares a 5-byte stack buffer and passes it to i2c_smbus_read_block_data() to retrieve the 4-byte BLACKBOX_INFO response. i2c_smbus_read_block_data() does not honour caller buffer sizes -- it memcpy()s data.block[0] bytes from the SMBus transaction (where data.block[0] is the length byte returned by the slave device, up to I2C_SMBUS_BLOCK_MAX = 32):

memcpy(values, &data.block[1], data.block[0]);

If the device returns any block length above 5, the call overflows the caller's 5-byte stack buffer before the post-call

if (ret != 4) return -EIO;

check has a chance to reject the response.

Widen the local buffer to I2C_SMBUS_BLOCK_MAX so the helper has room for any well-formed SMBus block response, matching the convention used by the other i2c_smbus_read_block_data() callers in this driver.