[all-commits] [llvm/llvm-project] 3d2925: [win/asan] AllocateMemoryForTrampoline within 2 GB...

[Hans via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 3d2925b9de0d60694a9f28edd2419f8eed34f1a1
      https://github.com/llvm/llvm-project/commit/3d2925b9de0d60694a9f28edd2419f8eed34f1a1
  Author: Hans <hans at hanshq.net>
  Date:   2024-09-18 (Wed, 18 Sep 2024)

  Changed paths:
    M compiler-rt/lib/interception/interception_win.cpp

  Log Message:
  -----------
  [win/asan] AllocateMemoryForTrampoline within 2 GB of the module's base address (#108822)

Since we may copy code (see CopyInstructions) to the trampoline which
could reference data inside the original module, we really want the
trampoline to be within 2 GB of not just the original function, but
within anything that function may have rip-relative accesses to, i.e.
within 2 GB of that function's whole module.

This fixes interception failures like the following scenario:

1. Intercept `CreateProcess` in kernel32.dll, allocating a trampoline
region right after
2. Start intercepting `memcpy` in the main executable, which is loaded
at a lower address than kernel32.dll, but still within 2 GB of the
trampoline region so we keep using it.
3. Try to copy instructions from `memcpy` to the trampoline. Turns out
one instruction references data that is more than 2GB away from the
trampoline, so it can't be relocated.
4. The process exits due to a CHECK failure

(Full story at https://crbug.com/341936875#comment45 and following.)



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