[all-commits] [llvm/llvm-project] ddf1de: [hwasan] Fix rare false negative (zero tag) in sta...

[Thurston Dang via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: ddf1de20a3f7db3bca1ef6ba7e6cbb90aac5fd2d
      https://github.com/llvm/llvm-project/commit/ddf1de20a3f7db3bca1ef6ba7e6cbb90aac5fd2d
  Author: Thurston Dang <thurston.dang at gmail.com>
  Date:   2023-10-18 (Wed, 18 Oct 2023)

  Changed paths:
    M compiler-rt/test/hwasan/TestCases/deep-recursion.c
    M compiler-rt/test/hwasan/TestCases/stack-uar.c

  Log Message:
  -----------
  [hwasan] Fix rare false negative (zero tag) in stack-uar.c (#69374)

stack-uar.c is flaky (1 in 256 executions) because the random tag
may be zero (https://github.com/llvm/llvm-project/issues/69221).

This patch works around the issue in the same way as deep-recursion.c

(https://github.com/llvm/llvm-project/commit/aa4dfd3736dd1c2e0263eacd09bd613c5784ea73),
by falling back to a neighboring object, which must have a different
(non-zero) tag.

This patch also does a minor cleanup of the aforementioned
deep-recursion.c, for consistency with stack-uar.c.

Co-authored-by: Thurston Dang <thurston at google.com>