From: VanshAgarwal24036 <148854295+VanshAgarwal24036@users.noreply.github.com>
Date: Fri, 13 Mar 2026 12:15:26 +0000 (+0530)
Subject: gh-145792: Fix incorrect alloca allocation size in traceback.c (#145814)
X-Git-Tag: v3.15.0a8~327
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=59d97683c19923b06e2b2110efadb90fe37f53f3;p=thirdparty%2FPython%2Fcpython.git

gh-145792: Fix incorrect alloca allocation size in traceback.c (#145814)
---

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-03-11-19-09-47.gh-issue-145792.X5KUhc.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-03-11-19-09-47.gh-issue-145792.X5KUhc.rst
new file mode 100644
index 000000000000..bd42f32d6ae3
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-03-11-19-09-47.gh-issue-145792.X5KUhc.rst
@@ -0,0 +1,2 @@
+Fix out-of-bounds access when invoking faulthandler on a CPython build
+compiled without support for VLAs.
diff --git a/Python/traceback.c b/Python/traceback.c
index 74360a1c73c2..1e8c9c879f9a 100644
--- a/Python/traceback.c
+++ b/Python/traceback.c
@@ -41,7 +41,7 @@
 
 #if defined(__STDC_NO_VLA__) && (__STDC_NO_VLA__ == 1)
 /* Use alloca() for VLAs. */
-#  define VLA(type, name, size) type *name = alloca(size)
+#  define VLA(type, name, size) type *name = alloca(sizeof(type) * (size))
 #elif !defined(__STDC_NO_VLA__) || (__STDC_NO_VLA__ == 0)
 /* Use actual C VLAs.*/
 #  define VLA(type, name, size) type name[size]