From: Rich Felker <dalias@aerifal.cx>
Date: Tue, 17 Apr 2018 19:18:49 +0000 (-0400)
Subject: comment __malloc_donate overflow logic
X-Git-Tag: v1.1.20~120
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=14032c30e2d41e5c0dac25d399f7086f74d4e0c8;p=oweals%2Fmusl.git

comment __malloc_donate overflow logic
---

diff --git a/src/malloc/malloc.c b/src/malloc/malloc.c
index 6605ec3a..991300cc 100644
--- a/src/malloc/malloc.c
+++ b/src/malloc/malloc.c
@@ -563,6 +563,9 @@ void __malloc_donate(char *start, char *end)
 	size_t align_start_up = (SIZE_ALIGN-1) & (-(uintptr_t)start - OVERHEAD);
 	size_t align_end_down = (SIZE_ALIGN-1) & (uintptr_t)end;
 
+	/* Getting past this condition ensures that the padding for alignment
+	 * and header overhead will not overflow and will leave a nonzero
+	 * multiple of SIZE_ALIGN bytes between start and end. */
 	if (end - start <= OVERHEAD + align_start_up + align_end_down)
 		return;
 	start += align_start_up + OVERHEAD;