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    SubjectRe: When was ASLR introduced in the Linux kernel?
    Le mardi 30 novembre 2010 à 12:47 +0100, Victor van der Veen a écrit :
    > Hi,
    > - When was ASLR introduced in the Linux kernel (not PaX/ExecShield)?
    > - When was ASLR enabled by default?
    > - What's the current state of ASLR in the Linux kernel? Is it still
    > under development? Or should we rely on the PaX/ExecShield patches?
    > Wikipedia states that "a weak form of ASLR exists in the linux kernel
    > since version 2.6.12 (June 2005)", but I could not find any proof that
    > backs this up. I grepped changelogs of the entire 2.6 kernel, but I was
    > unable to find any relevant information. Grepping the source code did
    > not help either. Any more Google results all quote the same wikipedia
    > line.


    echo val >/proc/sys/kernel/randomize_va_space

    vi +391 Documentation/sysctl/kernel.txt

    This option can be used to select the type of process address
    space randomization that is used in the system, for architectures
    that support this feature.

    0 - Turn the process address space randomization off. This is the
    default for architectures that do not support this feature anyways,
    and kernels that are booted with the "norandmaps" parameter.

    1 - Make the addresses of mmap base, stack and VDSO page randomized.
    This, among other things, implies that shared libraries will be
    loaded to random addresses. Also for PIE-linked binaries, the
    location of code start is randomized. This is the default if the
    CONFIG_COMPAT_BRK option is enabled.

    2 - Additionally enable heap randomization. This is the default if
    CONFIG_COMPAT_BRK is disabled.

    There are a few legacy applications out there (such as some ancient
    versions of from 1996) that assume that brk area starts
    just after the end of the code+bss. These applications break when
    start of the brk area is randomized. There are however no known
    non-legacy applications that would be broken this way, so for most
    systems it is safe to choose full randomization.

    Systems with ancient and/or broken binaries should be configured
    with CONFIG_COMPAT_BRK enabled, which excludes the heap from process
    address space randomization.

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