Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 341e30e628ef34306363a6af1ee18ea4a4955088
https://github.com/WebKit/WebKit/commit/341e30e628ef34306363a6af1ee18ea4a4955088
Author: Marcus Plutowski <[email protected]>
Date: 2024-09-11 (Wed, 11 Sep 2024)
Changed paths:
M Source/WTF/wtf/posix/OSAllocatorPOSIX.cpp
Log Message:
-----------
Remove OSAllocator's legacy manual impl of ASLR on x86
https://bugs.webkit.org/show_bug.cgi?id=279273
rdar://135430256
Reviewed by Yusuke Suzuki and Sam Weinig.
This has not been necessary for a long time: if you pass mmap a nullptr
for the address, the kernel will select a suitably random location on
its own.
Doing it ourselves is bad for multiple reasons:
1) it’s slower,
2) it's confusing,
3) selecting a specific location in memory is generally suspicious, and
could stress kernel-internal code paths which are not used much
elsewhere -- increasing the likelihood of running into a bug.
However, this situation does raise the specter of Chesterton’s Fence: if
the OS does this automatically, then why did we ever implement code to
do it ourselves? The answer is that this code is just really old: the
first patch adding this to the codebase (34933@main) was committed in
April 2009, and the code has not been touched since December 2010
(63979@main). ASLR was only implemented on Mac OS X in version 10.5
(Leopard, released October 2007) and only expanded to cover all
applications in 10.7 (Lion, July 2011). So this code was written during
a time when we _did_ need to implement it ourselves; as that is no
longer the case, we should stop doing so.
* Source/WTF/wtf/posix/OSAllocatorPOSIX.cpp:
(WTF::OSAllocator::tryReserveAndCommit): stop rolling our own ASLR
Canonical link: https://commits.webkit.org/283483@main
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