diff options
Diffstat (limited to 'malloc/malloc.c')
| -rw-r--r-- | malloc/malloc.c | 112 |
1 files changed, 48 insertions, 64 deletions
diff --git a/malloc/malloc.c b/malloc/malloc.c index 801ba1f..0e3d4dd 100644 --- a/malloc/malloc.c +++ b/malloc/malloc.c @@ -1187,17 +1187,6 @@ nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ((uintptr_t)(MALLOC_ALIGNMENT == 2 * SIZE_SZ ? (p) : chunk2mem (p)) \ & MALLOC_ALIGN_MASK) - -/* - Check if a request is so large that it would wrap around zero when - padded and aligned. To simplify some other code, the bound is made - low enough so that adding MINSIZE will also not wrap around zero. - */ - -#define REQUEST_OUT_OF_RANGE(req) \ - ((unsigned long) (req) >= \ - (unsigned long) (INTERNAL_SIZE_T) (-2 * MINSIZE)) - /* pad request bytes into a usable size -- internal version */ #define request2size(req) \ @@ -1205,21 +1194,18 @@ nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ MINSIZE : \ ((req) + SIZE_SZ + MALLOC_ALIGN_MASK) & ~MALLOC_ALIGN_MASK) -/* Same, except also perform an argument and result check. First, we check - that the padding done by request2size didn't result in an integer - overflow. Then we check (using REQUEST_OUT_OF_RANGE) that the resulting - size isn't so large that a later alignment would lead to another integer - overflow. */ -#define checked_request2size(req, sz) \ -({ \ - (sz) = request2size (req); \ - if (((sz) < (req)) \ - || REQUEST_OUT_OF_RANGE (sz)) \ - { \ - __set_errno (ENOMEM); \ - return 0; \ - } \ -}) +/* Check if REQ overflows when padded and aligned and if the resulting value + is less than PTRDIFF_T. Returns TRUE and the requested size or MINSIZE in + case the value is less than MINSIZE on SZ or false if any of the previous + check fail. */ +static inline bool +checked_request2size (size_t req, size_t *sz) __nonnull (1) +{ + if (__glibc_unlikely (req > PTRDIFF_MAX)) + return false; + *sz = request2size (req); + return true; +} /* --------------- Physical chunk operations --------------- @@ -3037,6 +3023,9 @@ __libc_malloc (size_t bytes) mstate ar_ptr; void *victim; + _Static_assert (PTRDIFF_MAX <= SIZE_MAX / 2, + "PTRDIFF_MAX is not more than half of SIZE_MAX"); + void *(*hook) (size_t, const void *) = atomic_forced_read (__malloc_hook); if (__builtin_expect (hook != NULL, 0)) @@ -3044,7 +3033,11 @@ __libc_malloc (size_t bytes) #if USE_TCACHE /* int_free also calls request2size, be careful to not pad twice. */ size_t tbytes; - checked_request2size (bytes, tbytes); + if (!checked_request2size (bytes, &tbytes)) + { + __set_errno (ENOMEM); + return NULL; + } size_t tc_idx = csize2tidx (tbytes); MAYBE_INIT_TCACHE (); @@ -3181,7 +3174,11 @@ __libc_realloc (void *oldmem, size_t bytes) && !DUMPED_MAIN_ARENA_CHUNK (oldp)) malloc_printerr ("realloc(): invalid pointer"); - checked_request2size (bytes, nb); + if (!checked_request2size (bytes, &nb)) + { + __set_errno (ENOMEM); + return NULL; + } if (chunk_is_mmapped (oldp)) { @@ -3291,13 +3288,6 @@ _mid_memalign (size_t alignment, size_t bytes, void *address) return 0; } - /* Check for overflow. */ - if (bytes > SIZE_MAX - alignment - MINSIZE) - { - __set_errno (ENOMEM); - return 0; - } - /* Make sure alignment is power of 2. */ if (!powerof2 (alignment)) @@ -3357,14 +3347,16 @@ __libc_pvalloc (size_t bytes) void *address = RETURN_ADDRESS (0); size_t pagesize = GLRO (dl_pagesize); - size_t rounded_bytes = ALIGN_UP (bytes, pagesize); - - /* Check for overflow. */ - if (bytes > SIZE_MAX - 2 * pagesize - MINSIZE) + size_t rounded_bytes; + /* ALIGN_UP with overflow check. */ + if (__glibc_unlikely (__builtin_add_overflow (bytes, + pagesize - 1, + &rounded_bytes))) { __set_errno (ENOMEM); return 0; } + rounded_bytes = rounded_bytes & -(pagesize - 1); return _mid_memalign (pagesize, rounded_bytes, address); } @@ -3374,30 +3366,24 @@ __libc_calloc (size_t n, size_t elem_size) { mstate av; mchunkptr oldtop, p; - INTERNAL_SIZE_T bytes, sz, csz, oldtopsize; + INTERNAL_SIZE_T sz, csz, oldtopsize; void *mem; unsigned long clearsize; unsigned long nclears; INTERNAL_SIZE_T *d; + ptrdiff_t bytes; - /* size_t is unsigned so the behavior on overflow is defined. */ - bytes = n * elem_size; -#define HALF_INTERNAL_SIZE_T \ - (((INTERNAL_SIZE_T) 1) << (8 * sizeof (INTERNAL_SIZE_T) / 2)) - if (__builtin_expect ((n | elem_size) >= HALF_INTERNAL_SIZE_T, 0)) + if (__glibc_unlikely (__builtin_mul_overflow (n, elem_size, &bytes))) { - if (elem_size != 0 && bytes / elem_size != n) - { - __set_errno (ENOMEM); - return 0; - } + __set_errno (ENOMEM); + return NULL; } + sz = bytes; void *(*hook) (size_t, const void *) = atomic_forced_read (__malloc_hook); if (__builtin_expect (hook != NULL, 0)) { - sz = bytes; mem = (*hook)(sz, RETURN_ADDRESS (0)); if (mem == 0) return 0; @@ -3405,8 +3391,6 @@ __libc_calloc (size_t n, size_t elem_size) return memset (mem, 0, sz); } - sz = bytes; - MAYBE_INIT_TCACHE (); if (SINGLE_THREAD_P) @@ -3553,12 +3537,16 @@ _int_malloc (mstate av, size_t bytes) Convert request size to internal form by adding SIZE_SZ bytes overhead plus possibly more to obtain necessary alignment and/or to obtain a size of at least MINSIZE, the smallest allocatable - size. Also, checked_request2size traps (returning 0) request sizes + size. Also, checked_request2size returns false for request sizes that are so large that they wrap around zero when padded and aligned. */ - checked_request2size (bytes, nb); + if (!checked_request2size (bytes, &nb)) + { + __set_errno (ENOMEM); + return NULL; + } /* There are no usable arenas. Fall back to sysmalloc to get a chunk from mmap. */ @@ -4680,21 +4668,17 @@ _int_memalign (mstate av, size_t alignment, size_t bytes) - checked_request2size (bytes, nb); + if (!checked_request2size (bytes, &nb)) + { + __set_errno (ENOMEM); + return NULL; + } /* Strategy: find a spot within that chunk that meets the alignment request, and then possibly free the leading and trailing space. */ - - /* Check for overflow. */ - if (nb > SIZE_MAX - alignment - MINSIZE) - { - __set_errno (ENOMEM); - return 0; - } - /* Call malloc with worst case padding to hit alignment. */ m = (char *) (_int_malloc (av, nb + alignment + MINSIZE)); |