From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sun, 14 Jul 2024 22:37:50 +0000 (+0100)
Subject: alloc.c: ckd_add, not by-hand checks
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=a51474e9e5f0999dcdf7ff5d24e3cad9a6939eba;p=emacs.git

alloc.c: ckd_add, not by-hand checks

* src/alloc.c (lmalloc, lrealloc): Prefer ckd_add to
by-hand checks for integer addition overflow.

(cherry picked from commit b77abd2bfeb13ae046b1f8c6157bd5a497665657)
---

diff --git a/src/alloc.c b/src/alloc.c
index 37069ee4c9e..52f8a65d59d 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -1404,8 +1404,8 @@ lmalloc (size_t size, bool clearit)
       if (laligned (p, size) && (MALLOC_0_IS_NONNULL || size || p))
 	return p;
       free (p);
-      size_t bigger = size + LISP_ALIGNMENT;
-      if (size < bigger)
+      size_t bigger;
+      if (!ckd_add (&bigger, size, LISP_ALIGNMENT))
 	size = bigger;
     }
 }
@@ -1418,8 +1418,8 @@ lrealloc (void *p, size_t size)
       p = realloc (p, size);
       if (laligned (p, size) && (size || p))
 	return p;
-      size_t bigger = size + LISP_ALIGNMENT;
-      if (size < bigger)
+      size_t bigger;
+      if (!ckd_add (&bigger, size, LISP_ALIGNMENT))
 	size = bigger;
     }
 }