[libc] __stack_chk_fail post submit test failures

[nickdesaulniers]

Use a size smaller than the smallest supported page size so that we don't
clobber over any guard pages, which may result in a segfault before
__stack_chk_fail can be called.

[llvmbot]

@llvm/pr-subscribers-libc

Author: Nick Desaulniers (nickdesaulniers)

Changes

Use a size smaller than the smallest supported page size so that we don't
clobber over any guard pages, which may result in a segfault before
__stack_chk_fail can be called.

---

Full diff: https://github.com/llvm/llvm-project/pull/75962.diff

1 Files Affected:

• (modified) libc/test/src/compiler/stack_chk_guard_test.cpp (+1-1)

diff --git a/libc/test/src/compiler/stack_chk_guard_test.cpp b/libc/test/src/compiler/stack_chk_guard_test.cpp
index 1de2d1b7357f70..df15962acd9678 100644
--- a/libc/test/src/compiler/stack_chk_guard_test.cpp
+++ b/libc/test/src/compiler/stack_chk_guard_test.cpp
@@ -20,7 +20,7 @@ TEST(LlvmLibcStackChkFail, Smash) {
   EXPECT_DEATH(
       [] {
         int arr[20];
-        LIBC_NAMESPACE::memset(arr, 0xAA, 9001);
+        LIBC_NAMESPACE::memset(arr, 0xAA, 2001);
       },
       WITH_SIGNAL(SIGABRT));
 }

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[michaelrj-google]

LGTM, but possibly add a comment about this specific function needing extern "C" instead of the usual namespace.