From b50dd3bc8cbb1efe85399b03d7e6c0310c2ead84 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Mon, 31 Dec 2018 22:04:36 +0100 Subject: malloc: Always call memcpy in _int_realloc [BZ #24027] This commit removes the custom memcpy implementation from _int_realloc for small chunk sizes. The ncopies variable has the wrong type, and an integer wraparound could cause the existing code to copy too few elements (leaving the new memory region mostly uninitialized). Therefore, removing this code fixes bug 24027. --- ChangeLog | 7 +++++++ malloc/malloc.c | 43 +------------------------------------------ 2 files changed, 8 insertions(+), 42 deletions(-) diff --git a/ChangeLog b/ChangeLog index 3edcb832b9..27331bc15e 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,10 @@ +2018-12-31 Florian Weimer + + [BZ #24027] + * malloc/malloc.c (_int_realloc): Always call memcpy for the + copying operation. (ncopies had the wrong type, resulting in an + integer wraparound and too few elements being copied.) + 2018-12-31 H.J. Lu [BZ #24022] diff --git a/malloc/malloc.c b/malloc/malloc.c index c33709e966..0a20a6054c 100644 --- a/malloc/malloc.c +++ b/malloc/malloc.c @@ -4581,11 +4581,6 @@ _int_realloc(mstate av, mchunkptr oldp, INTERNAL_SIZE_T oldsize, mchunkptr remainder; /* extra space at end of newp */ unsigned long remainder_size; /* its size */ - unsigned long copysize; /* bytes to copy */ - unsigned int ncopies; /* INTERNAL_SIZE_T words to copy */ - INTERNAL_SIZE_T* s; /* copy source */ - INTERNAL_SIZE_T* d; /* copy destination */ - /* oldmem size */ if (__builtin_expect (chunksize_nomask (oldp) <= 2 * SIZE_SZ, 0) || __builtin_expect (oldsize >= av->system_mem, 0)) @@ -4653,43 +4648,7 @@ _int_realloc(mstate av, mchunkptr oldp, INTERNAL_SIZE_T oldsize, } else { - /* - Unroll copy of <= 36 bytes (72 if 8byte sizes) - We know that contents have an odd number of - INTERNAL_SIZE_T-sized words; minimally 3. - */ - - copysize = oldsize - SIZE_SZ; - s = (INTERNAL_SIZE_T *) (chunk2mem (oldp)); - d = (INTERNAL_SIZE_T *) (newmem); - ncopies = copysize / sizeof (INTERNAL_SIZE_T); - assert (ncopies >= 3); - - if (ncopies > 9) - memcpy (d, s, copysize); - - else - { - *(d + 0) = *(s + 0); - *(d + 1) = *(s + 1); - *(d + 2) = *(s + 2); - if (ncopies > 4) - { - *(d + 3) = *(s + 3); - *(d + 4) = *(s + 4); - if (ncopies > 6) - { - *(d + 5) = *(s + 5); - *(d + 6) = *(s + 6); - if (ncopies > 8) - { - *(d + 7) = *(s + 7); - *(d + 8) = *(s + 8); - } - } - } - } - + memcpy (newmem, chunk2mem (oldp), oldsize - SIZE_SZ); _int_free (av, oldp, 1); check_inuse_chunk (av, newp); return chunk2mem (newp); -- cgit v1.2.3