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What is address space layout randomization method?
Address Space Layout Randomization (ASLR) is a computer security technique which involves randomly positioning the base address of an executable and the position of libraries, heap, and stack, in a process’s address space.
What is virtual address space size?
The virtual address space for a process is the set of virtual memory addresses that it can use. The virtual address space for 32-bit Windows is 4 gigabytes (GB) in size and divided into two partitions: one for use by the process and the other reserved for use by the system.
How big is the address space for a kernel?
The current layout of the kernel’s virtual address space only leaves 512M for the kernel code—and 1.5G for modules. Since there is no need for that much module space, his patches reduce that to 1G, leaving 1G for the kernel, thus 512 possible slots (as it needs to be 2M aligned).
How big is the address space in Linux?
For example, on a 32-bit x86 machine running Linux, the kernel resides in the 0xc00000000–0xffffffff range (the “top” gigabyte of virtual memory), whereas each process is free to use all the addresses beneath this range (the “lower” 3GB of virtual memory).
How is the address space of a process determined?
The location of the split is determined by the value of PAGE_OFFSETwhich is at 0xC0000000on the x86. This means that 3GiB is available for the process to use while the remaining 1GiB is always mapped by the kernel. The linear virtual address space as the kernel sees it is illustrated in Figure ??. Figure 4.1: Kernel Address Space
How big is the address space in x86?
The patches are currently only for 64-bit x86, though Cook plans to look at ARM next. He knows a “lot less” about ARM, though, so he is hoping that he can “trick someone into helping me”, he said. The current layout of the kernel’s virtual address space only leaves 512M for the kernel code—and 1.5G for modules.