Meltdown is briefly

Meltdown & Spectre is the latest Meltdown and Spectre vulnerability in modern CPUS. It was first discovered by Google researchers that private data can be accessed through a memory-side channel timing attack. Chromium, Apple and Mozilla all published articles to discuss its impact on various platforms and countermeasures. This is how Meltdown works, Why Raspberry Pi Isn’t Vulnerable to Spectre or Meltdown. Meltdown in a Nutshell is the latest version of Meltdown in a Nutshell. This article summarizes the Use of Linux configuration, internal principles and Shell programming series.

For the following pseudocode:

x = readMemory_location_of_os_where_secret_lies) // Throws an exception y = arr[x *4096] // Reads local memory based on xCopy the code

Applications are compiled or interpreted as CPU instructions, and the first line of reading sensitive memory ends up throwing an exception, but due to the CPU’s Speculative Execution optimization, the second line of code runs before the CPU processes permission checks. The value of y has actually been read into the CPU cache. If the value of x is s, memory ARR [s * 4096] is read by the CPU. If the CPU finds that the process has no right to read data, it clears the x and y values. To optimize the read speed, the CPU caches the read values to the LOCAL CPU. The attacker takes advantage of this feature to launch a bypass attack. The attacker traverses all possible ARR [X *4096] addresses in a brute-force manner. According to the timer to determine which address is the fastest to read, that is, the value of X s can be obtained. By analogy, ‘e’, ‘C’, ‘r’, ‘e’, ‘t’ can be obtained.