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author | Hans Wennborg <hans@chromium.org> | 2023-04-13 09:53:06 +0200 |
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committer | Hans Wennborg <hans@chromium.org> | 2023-04-13 09:53:06 +0200 |
commit | 4a2da7e8a91bd381ee38fbeb6055e7d97453a789 (patch) | |
tree | 05cc9ff02ab5fdaeb3777d06a7c0d016de48728c /compiler-rt | |
parent | 9d0b55f0e4ca55d04ee8abfdf021913ea3c30082 (diff) | |
download | llvm-4a2da7e8a91bd381ee38fbeb6055e7d97453a789.zip llvm-4a2da7e8a91bd381ee38fbeb6055e7d97453a789.tar.gz llvm-4a2da7e8a91bd381ee38fbeb6055e7d97453a789.tar.bz2 |
Revert "ASan: move allocator base to avoid conflict with high-entropy ASLR for x86-64 Linux"
This broke lit tests on Mac, see comment on the code review.
> Users have discovered [*] that when CONFIG_ARCH_MMAP_RND_BITS == 32,
> it will frequently conflict with ASan's allocator on x86-64 Linux, because the
> PIE program segment base address of 0x555555555554 plus an ASLR shift of up to
> ((2**32) * 4K == 0x100000000000) will sometimes exceed ASan's hardcoded
> base address of 0x600000000000. We fix this by simply moving the allocator base
> to 0x500000000000, which is below the PIE program segment base address. This is
> cleaner than trying to move it to another location that is sandwiched between
> the PIE program and library segments, because if either of those grow too large,
> it will collide with the allocator region.
>
> Note that we will never need to change this base address again (unless we want to increase
> the size of the allocator), because ASLR cannot be set above 32-bits for x86-64 Linux (the
> PIE program segment and library segments would collide with each other; see also
> ARCH_MMAP_RND_BITS_MAX in https://github.com/torvalds/linux/blob/master/arch/x86/Kconfig).
>
> [*] see https://b.corp.google.com/issues/276925478
> and https://groups.google.com/a/google.com/g/chrome-os-gardeners/c/BbfzCP3dEeo/m/h3C_vVUxCQAJ
>
> Differential Revision: https://reviews.llvm.org/D147984
This reverts commit 6f42b97a29a5872c115029c615f55f33419a4c1f.
Diffstat (limited to 'compiler-rt')
-rw-r--r-- | compiler-rt/lib/asan/asan_allocator.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/compiler-rt/lib/asan/asan_allocator.h b/compiler-rt/lib/asan/asan_allocator.h index 05dcd2d..0b4dbf0 100644 --- a/compiler-rt/lib/asan/asan_allocator.h +++ b/compiler-rt/lib/asan/asan_allocator.h @@ -144,7 +144,7 @@ const uptr kAllocatorSpace = ~(uptr)0; const uptr kAllocatorSize = 0x8000000000ULL; // 500G typedef DefaultSizeClassMap SizeClassMap; # else -const uptr kAllocatorSpace = 0x500000000000ULL; +const uptr kAllocatorSpace = 0x600000000000ULL; const uptr kAllocatorSize = 0x40000000000ULL; // 4T. typedef DefaultSizeClassMap SizeClassMap; # endif |