patch 8.1.1827: allocating more memory than needed for extended structs commit https://github.com/vim/vim/commit/47ed553fd5bebfc36eb8aa81686eeaa5a84eccac Author: Bram Moolenaar <Bram@vim.org> Date: Thu Aug 8 20:49:14 2019 +0200 patch 8.1.1827: allocating more memory than needed for extended structs Problem: Allocating more memory than needed for extended structs. Solution: Use offsetof() instead of sizeof(). (Dominique Pelle, closes #4786)

--- a/src/regexp.c
+++ b/src/regexp.c
@@ -1319,7 +1319,7 @@ bt_regcomp(char_u *expr, int re_flags)
 	return NULL;
 
     /* Allocate space. */
-    r = alloc(sizeof(bt_regprog_T) + regsize);
+    r = alloc(offsetof(bt_regprog_T, program) + regsize);
     if (r == NULL)
 	return NULL;
     r->re_in_use = FALSE;