From d889cc3463edc92869676c1eec34a8f52d942adb Mon Sep 17 00:00:00 2001 From: Alexander Monakov Date: Mon, 16 Apr 2018 20:54:35 +0300 Subject: [PATCH] malloc: fix an over-allocation bug Fix an instance where realloc code would overallocate by OVERHEAD bytes amount. Manually arrange for reuse of memcpy-free-return exit sequence. --- src/malloc/malloc.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/src/malloc/malloc.c b/src/malloc/malloc.c index 0a7d5d85..db19bc34 100644 --- a/src/malloc/malloc.c +++ b/src/malloc/malloc.c @@ -414,10 +414,9 @@ void *realloc(void *p, size_t n) size_t newlen = n + extra; /* Crash on realloc of freed chunk */ if (extra & 1) a_crash(); - if (newlen < PAGE_SIZE && (new = malloc(n))) { - memcpy(new, p, n-OVERHEAD); - free(p); - return new; + if (newlen < PAGE_SIZE && (new = malloc(n-OVERHEAD))) { + n0 = n; + goto copy_free_ret; } newlen = (newlen + PAGE_SIZE-1) & -PAGE_SIZE; if (oldlen == newlen) return p; @@ -460,6 +459,7 @@ copy_realloc: /* As a last resort, allocate a new chunk and copy to it. */ new = malloc(n-OVERHEAD); if (!new) return 0; +copy_free_ret: memcpy(new, p, n0-OVERHEAD); free(CHUNK_TO_MEM(self)); return new; -- 2.25.1