[all-commits] [llvm/llvm-project] 868e1e: Revert "[libasan] Remove 4Mb stack limit for swapc...

[Vitaly Buka via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 868e1ee1d02c153d867a9f4e2b7e35df7d0701df
      https://github.com/llvm/llvm-project/commit/868e1ee1d02c153d867a9f4e2b7e35df7d0701df
  Author: Vitaly Buka <vitalybuka at google.com>
  Date:   2022-07-19 (Tue, 19 Jul 2022)

  Changed paths:
    M compiler-rt/lib/asan/asan_interceptors.cpp
    M compiler-rt/test/asan/TestCases/Linux/swapcontext_annotation.cpp

  Log Message:
  -----------
  Revert "[libasan] Remove 4Mb stack limit for swapcontext unpoisoning"

This patches exposed existing incorectness of swapcontext imlementation.
swapcontext does not set oucp->uc_stack. Unpoisoning works if ucp is
from makecontext, but may try to use garbage pointers if it's from
previos swapcontext or from getcontext. Existing limit reduces
probability of garbage pointers are used.

I restore behavour which we had for years, and will look to improve
swapcontext support.

This reverts commit d0751c9725aab1dad3d86481e13a4628356e7422.