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

VanshAgarwal24036 · web-flow · commit 59d97683c199 · 2026-03-13T13:15:26.000+01:00
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
@@ -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
@@ -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]

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+Fix out-of-bounds access when invoking faulthandler on a CPython build`
	`2`	`+compiled without support for VLAs.`