mirror of git://git.musl-libc.org/musl
eliminate OOB array hacks in malloc
This commit is contained in:
Rich Felker
parent
e22c2d3ee6
commit
5d0965cb56
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@ -16,9 +16,8 @@ void *__mremap(void *, size_t, size_t, int, ...);
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int __madvise(void *, size_t, int);
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struct chunk {
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size_t data[1];
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struct chunk *next;
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struct chunk *prev;
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size_t psize, csize;
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struct chunk *next, *prev;
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};
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struct bin {
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@ -44,19 +43,19 @@ static struct {
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#define DONTCARE 16
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#define RECLAIM 163840
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#define CHUNK_SIZE(c) ((c)->data[0] & SIZE_MASK)
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#define CHUNK_PSIZE(c) ((c)->data[-1] & SIZE_MASK)
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#define CHUNK_SIZE(c) ((c)->csize & SIZE_MASK)
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#define CHUNK_PSIZE(c) ((c)->psize & SIZE_MASK)
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#define PREV_CHUNK(c) ((struct chunk *)((char *)(c) - CHUNK_PSIZE(c)))
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#define NEXT_CHUNK(c) ((struct chunk *)((char *)(c) + CHUNK_SIZE(c)))
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#define MEM_TO_CHUNK(p) (struct chunk *)((size_t *)p - 1)
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#define CHUNK_TO_MEM(c) (void *)((c)->data+1)
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#define MEM_TO_CHUNK(p) (struct chunk *)((char *)(p) - OVERHEAD)
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#define CHUNK_TO_MEM(c) (void *)((char *)(c) + OVERHEAD)
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#define BIN_TO_CHUNK(i) (MEM_TO_CHUNK(&mal.bins[i].head))
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#define C_INUSE ((size_t)1)
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#define C_FLAGS ((size_t)3)
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#define C_SIZE SIZE_MASK
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#define IS_MMAPPED(c) !((c)->data[0] & (C_INUSE))
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#define IS_MMAPPED(c) !((c)->csize & (C_INUSE))
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/* Synchronization tools */
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@ -138,8 +137,8 @@ void __dump_heap(int x)
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for (c = (void *)mal.heap; CHUNK_SIZE(c); c = NEXT_CHUNK(c))
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fprintf(stderr, "base %p size %zu (%d) flags %d/%d\n",
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c, CHUNK_SIZE(c), bin_index(CHUNK_SIZE(c)),
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c->data[0] & 15,
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NEXT_CHUNK(c)->data[-1] & 15);
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c->csize & 15,
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NEXT_CHUNK(c)->psize & 15);
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for (i=0; i<64; i++) {
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if (mal.bins[i].head != BIN_TO_CHUNK(i) && mal.bins[i].head) {
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fprintf(stderr, "bin %d: %p\n", i, mal.bins[i].head);
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@ -165,11 +164,11 @@ static struct chunk *expand_heap(size_t n)
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if (__brk(new) != new) goto fail;
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w = MEM_TO_CHUNK(new);
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w->data[-1] = n | C_INUSE;
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w->data[0] = 0 | C_INUSE;
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w->psize = n | C_INUSE;
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w->csize = 0 | C_INUSE;
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w = MEM_TO_CHUNK(mal.brk);
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w->data[0] = n | C_INUSE;
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w->csize = n | C_INUSE;
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mal.brk = new;
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unlock(mal.brk_lock);
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@ -206,7 +205,7 @@ static int init_malloc(size_t n)
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}
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mal.heap = (void *)c;
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c->data[-1] = 0 | C_INUSE;
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c->psize = 0 | C_INUSE;
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free(CHUNK_TO_MEM(c));
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a_store(&init, 2);
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@ -236,18 +235,18 @@ static void unbin(struct chunk *c, int i)
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a_and_64(&mal.binmap, ~(1ULL<<i));
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c->prev->next = c->next;
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c->next->prev = c->prev;
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c->data[0] |= C_INUSE;
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NEXT_CHUNK(c)->data[-1] |= C_INUSE;
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c->csize |= C_INUSE;
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NEXT_CHUNK(c)->psize |= C_INUSE;
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}
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static int alloc_fwd(struct chunk *c)
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{
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int i;
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size_t k;
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while (!((k=c->data[0]) & C_INUSE)) {
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while (!((k=c->csize) & C_INUSE)) {
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i = bin_index(k);
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lock_bin(i);
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if (c->data[0] == k) {
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if (c->csize == k) {
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unbin(c, i);
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unlock_bin(i);
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return 1;
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@ -261,10 +260,10 @@ static int alloc_rev(struct chunk *c)
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{
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int i;
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size_t k;
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while (!((k=c->data[-1]) & C_INUSE)) {
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while (!((k=c->psize) & C_INUSE)) {
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i = bin_index(k);
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lock_bin(i);
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if (c->data[-1] == k) {
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if (c->psize == k) {
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unbin(PREV_CHUNK(c), i);
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unlock_bin(i);
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return 1;
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@ -301,10 +300,10 @@ static int pretrim(struct chunk *self, size_t n, int i, int j)
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split->next = self->next;
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split->prev->next = split;
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split->next->prev = split;
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split->data[-1] = n | C_INUSE;
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split->data[0] = n1-n;
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next->data[-1] = n1-n;
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self->data[0] = n | C_INUSE;
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split->psize = n | C_INUSE;
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split->csize = n1-n;
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next->psize = n1-n;
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self->csize = n | C_INUSE;
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return 1;
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}
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@ -318,10 +317,10 @@ static void trim(struct chunk *self, size_t n)
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next = NEXT_CHUNK(self);
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split = (void *)((char *)self + n);
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split->data[-1] = n | C_INUSE;
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split->data[0] = n1-n | C_INUSE;
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next->data[-1] = n1-n | C_INUSE;
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self->data[0] = n | C_INUSE;
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split->psize = n | C_INUSE;
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split->csize = n1-n | C_INUSE;
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next->psize = n1-n | C_INUSE;
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self->csize = n | C_INUSE;
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free(CHUNK_TO_MEM(split));
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}
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@ -338,9 +337,9 @@ void *malloc(size_t n)
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char *base = __mmap(0, len, PROT_READ|PROT_WRITE,
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MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
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if (base == (void *)-1) return 0;
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c = (void *)(base + SIZE_ALIGN - sizeof(size_t));
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c->data[0] = len - (SIZE_ALIGN - sizeof(size_t));
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c->data[-1] = SIZE_ALIGN - sizeof(size_t);
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c = (void *)(base + SIZE_ALIGN - OVERHEAD);
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c->csize = len - (SIZE_ALIGN - OVERHEAD);
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c->psize = SIZE_ALIGN - OVERHEAD;
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return CHUNK_TO_MEM(c);
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}
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@ -354,15 +353,15 @@ void *malloc(size_t n)
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if (alloc_rev(c)) {
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struct chunk *x = c;
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c = PREV_CHUNK(c);
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NEXT_CHUNK(x)->data[-1] = c->data[0] =
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x->data[0] + CHUNK_SIZE(c);
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NEXT_CHUNK(x)->psize = c->csize =
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x->csize + CHUNK_SIZE(c);
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}
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break;
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}
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j = first_set(mask);
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lock_bin(j);
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c = mal.bins[j].head;
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if (c != BIN_TO_CHUNK(j) && j == bin_index(c->data[0])) {
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if (c != BIN_TO_CHUNK(j) && j == bin_index(c->csize)) {
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if (!pretrim(c, n, i, j)) unbin(c, j);
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unlock_bin(j);
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break;
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@ -390,7 +389,7 @@ void *realloc(void *p, size_t n)
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n1 = n0 = CHUNK_SIZE(self);
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if (IS_MMAPPED(self)) {
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size_t extra = self->data[-1];
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size_t extra = self->psize;
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char *base = (char *)self - extra;
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size_t oldlen = n0 + extra;
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size_t newlen = n + extra;
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@ -407,7 +406,7 @@ void *realloc(void *p, size_t n)
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if (base == (void *)-1)
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return newlen < oldlen ? p : 0;
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self = (void *)(base + extra);
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self->data[0] = newlen - extra;
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self->csize = newlen - extra;
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return CHUNK_TO_MEM(self);
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}
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@ -425,8 +424,8 @@ void *realloc(void *p, size_t n)
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self = PREV_CHUNK(self);
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n1 += CHUNK_SIZE(self);
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}
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self->data[0] = n1 | C_INUSE;
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next->data[-1] = n1 | C_INUSE;
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self->csize = n1 | C_INUSE;
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next->psize = n1 | C_INUSE;
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/* If we got enough space, split off the excess and return */
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if (n <= n1) {
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@ -454,7 +453,7 @@ void free(void *p)
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if (!p) return;
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if (IS_MMAPPED(self)) {
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size_t extra = self->data[-1];
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size_t extra = self->psize;
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char *base = (char *)self - extra;
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size_t len = CHUNK_SIZE(self) + extra;
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/* Crash on double free */
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@ -468,7 +467,7 @@ void free(void *p)
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for (;;) {
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/* Replace middle of large chunks with fresh zero pages */
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if (reclaim && (self->data[-1] & next->data[0] & C_INUSE)) {
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if (reclaim && (self->psize & next->csize & C_INUSE)) {
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uintptr_t a = (uintptr_t)self + SIZE_ALIGN+PAGE_SIZE-1 & -PAGE_SIZE;
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uintptr_t b = (uintptr_t)next - SIZE_ALIGN & -PAGE_SIZE;
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#if 1
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@ -479,13 +478,13 @@ void free(void *p)
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#endif
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}
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if (self->data[-1] & next->data[0] & C_INUSE) {
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self->data[0] = final_size | C_INUSE;
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next->data[-1] = final_size | C_INUSE;
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if (self->psize & next->csize & C_INUSE) {
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self->csize = final_size | C_INUSE;
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next->psize = final_size | C_INUSE;
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i = bin_index(final_size);
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lock_bin(i);
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lock(mal.free_lock);
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if (self->data[-1] & next->data[0] & C_INUSE)
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if (self->psize & next->csize & C_INUSE)
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break;
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unlock(mal.free_lock);
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unlock_bin(i);
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@ -508,8 +507,8 @@ void free(void *p)
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}
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}
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self->data[0] = final_size;
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next->data[-1] = final_size;
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self->csize = final_size;
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next->psize = final_size;
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unlock(mal.free_lock);
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self->next = BIN_TO_CHUNK(i);
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