diff options
Diffstat (limited to 'malloc')
| -rw-r--r-- | malloc/malloc.c | 163 |
1 files changed, 118 insertions, 45 deletions
diff --git a/malloc/malloc.c b/malloc/malloc.c index 4a65f520d7..03bc5569b9 100644 --- a/malloc/malloc.c +++ b/malloc/malloc.c @@ -523,6 +523,14 @@ do { \ #define MAP_ANONYMOUS MAP_ANON #endif +#ifndef MAP_NORESERVE +# ifdef MAP_AUTORESRV +# define MAP_NORESERVE MAP_AUTORESRV +# else +# define MAP_NORESERVE 0 +# endif +#endif + #endif /* HAVE_MMAP */ /* @@ -1757,15 +1765,15 @@ __malloc_check_init() static int dev_zero_fd = -1; /* Cached file descriptor for /dev/zero. */ -#define MMAP(size, prot) ((dev_zero_fd < 0) ? \ +#define MMAP(size, prot, flags) ((dev_zero_fd < 0) ? \ (dev_zero_fd = open("/dev/zero", O_RDWR), \ - mmap(0, (size), (prot), MAP_PRIVATE, dev_zero_fd, 0)) : \ - mmap(0, (size), (prot), MAP_PRIVATE, dev_zero_fd, 0)) + mmap(0, (size), (prot), (flags), dev_zero_fd, 0)) : \ + mmap(0, (size), (prot), (flags), dev_zero_fd, 0)) #else -#define MMAP(size, prot) \ - (mmap(0, (size), (prot), MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)) +#define MMAP(size, prot, flags) \ + (mmap(0, (size), (prot), (flags)|MAP_ANONYMOUS, -1, 0)) #endif @@ -1791,7 +1799,7 @@ mmap_chunk(size) size_t size; */ size = (size + SIZE_SZ + page_mask) & ~page_mask; - p = (mchunkptr)MMAP(size, PROT_READ|PROT_WRITE); + p = (mchunkptr)MMAP(size, PROT_READ|PROT_WRITE, MAP_PRIVATE); if(p == (mchunkptr) MAP_FAILED) return 0; n_mmaps++; @@ -1920,7 +1928,11 @@ new_heap(size) size_t size; size = HEAP_MAX_SIZE; size = (size + page_mask) & ~page_mask; - p1 = (char *)MMAP(HEAP_MAX_SIZE<<1, PROT_NONE); + /* A memory region aligned to a multiple of HEAP_MAX_SIZE is needed. + No swap space needs to be reserved for the following large + mapping (on Linux, this is the case for all non-writable mappings + anyway). */ + p1 = (char *)MMAP(HEAP_MAX_SIZE<<1, PROT_NONE, MAP_PRIVATE|MAP_NORESERVE); if(p1 == MAP_FAILED) return 0; p2 = (char *)(((unsigned long)p1 + HEAP_MAX_SIZE) & ~(HEAP_MAX_SIZE-1)); @@ -2014,6 +2026,7 @@ arena_get2(a_tsd, size) arena *a_tsd; size_t size; } /* Check the global, circularly linked list for available arenas. */ + repeat: do { if(!mutex_trylock(&a->mutex)) { THREAD_STAT(++(a->stat_lock_loop)); @@ -2023,6 +2036,16 @@ arena_get2(a_tsd, size) arena *a_tsd; size_t size; a = a->next; } while(a != a_tsd); + /* If not even the list_lock can be obtained, try again. This can + happen during `atfork', or for example on systems where thread + creation makes it temporarily impossible to obtain _any_ + locks. */ + if(mutex_trylock(&list_lock)) { + a = a_tsd; + goto repeat; + } + (void)mutex_unlock(&list_lock); + /* Nothing immediately available, so generate a new arena. */ h = new_heap(size + (sizeof(*h) + sizeof(*a) + MALLOC_ALIGNMENT)); if(!h) @@ -3780,9 +3803,6 @@ malloc_update_mallinfo(ar_ptr, mi) arena *ar_ptr; struct mallinfo *mi; #endif INTERNAL_SIZE_T avail; - /* Initialize the memory. */ - memset (mi, '\0', sizeof (struct mallinfo)); - (void)mutex_lock(&ar_ptr->mutex); avail = chunksize(top(ar_ptr)); navail = ((long)(avail) >= (long)MINSIZE)? 1 : 0; @@ -3806,6 +3826,7 @@ malloc_update_mallinfo(ar_ptr, mi) arena *ar_ptr; struct mallinfo *mi; mi->arena = ar_ptr->size; mi->ordblks = navail; + mi->smblks = mi->usmblks = mi->fsmblks = 0; /* clear unused fields */ mi->uordblks = ar_ptr->size - avail; mi->fordblks = avail; mi->hblks = n_mmaps; @@ -4136,13 +4157,39 @@ mALLOC_SET_STATe(msptr) Void_t* msptr; /* A simple, standard set of debugging hooks. Overhead is `only' one byte per chunk; still this will catch most cases of double frees or - overruns. */ + overruns. The goal here is to avoid obscure crashes due to invalid + usage, unlike in the MALLOC_DEBUG code. */ #define MAGICBYTE(p) ( ( ((size_t)p >> 3) ^ ((size_t)p >> 11)) & 0xFF ) +/* Instrument a chunk with overrun detector byte(s) and convert it + into a user pointer with requested size sz. */ + +static Void_t* +#if __STD_C +chunk2mem_check(mchunkptr p, size_t sz) +#else +chunk2mem_check(p, sz) mchunkptr p; size_t sz; +#endif +{ + unsigned char* m_ptr = (unsigned char*)chunk2mem(p); + size_t i; + + for(i = chunksize(p) - (chunk_is_mmapped(p) ? 2*SIZE_SZ+1 : SIZE_SZ+1); + i > sz; + i -= 0xFF) { + if(i-sz < 0x100) { + m_ptr[i] = (unsigned char)(i-sz); + break; + } + m_ptr[i] = 0xFF; + } + m_ptr[sz] = MAGICBYTE(p); + return (Void_t*)m_ptr; +} + /* Convert a pointer to be free()d or realloc()ed to a valid chunk - pointer. If the provided pointer is not valid, return NULL. The - goal here is to avoid crashes, unlike in the MALLOC_DEBUG code. */ + pointer. If the provided pointer is not valid, return NULL. */ static mchunkptr internal_function @@ -4153,7 +4200,8 @@ mem2chunk_check(mem) Void_t* mem; #endif { mchunkptr p; - INTERNAL_SIZE_T sz; + INTERNAL_SIZE_T sz, c; + unsigned char magic; p = mem2chunk(mem); if(!aligned_OK(p)) return NULL; @@ -4166,9 +4214,11 @@ mem2chunk_check(mem) Void_t* mem; (long)prev_chunk(p)<(long)sbrk_base || next_chunk(prev_chunk(p))!=p) )) return NULL; - if(*((unsigned char*)p + sz + (SIZE_SZ-1)) != MAGICBYTE(p)) - return NULL; - *((unsigned char*)p + sz + (SIZE_SZ-1)) ^= 0xFF; + magic = MAGICBYTE(p); + for(sz += SIZE_SZ-1; (c = ((unsigned char*)p)[sz]) != magic; sz -= c) { + if(c<=0 || sz<(c+2*SIZE_SZ)) return NULL; + } + ((unsigned char*)p)[sz] ^= 0xFF; } else { unsigned long offset, page_mask = malloc_getpagesize-1; @@ -4184,13 +4234,53 @@ mem2chunk_check(mem) Void_t* mem; ( (((unsigned long)p - p->prev_size) & page_mask) != 0 ) || ( (sz = chunksize(p)), ((p->prev_size + sz) & page_mask) != 0 ) ) return NULL; - if(*((unsigned char*)p + sz - 1) != MAGICBYTE(p)) - return NULL; - *((unsigned char*)p + sz - 1) ^= 0xFF; + magic = MAGICBYTE(p); + for(sz -= 1; (c = ((unsigned char*)p)[sz]) != magic; sz -= c) { + if(c<=0 || sz<(c+2*SIZE_SZ)) return NULL; + } + ((unsigned char*)p)[sz] ^= 0xFF; } return p; } +/* Check for corruption of the top chunk, and try to recover if + necessary. */ + +static int +top_check() +{ + mchunkptr t = top(&main_arena); + char* brk, * new_brk; + INTERNAL_SIZE_T front_misalign, sbrk_size; + unsigned long pagesz = malloc_getpagesize; + + if((char*)t + chunksize(t) == sbrk_base + sbrked_mem || + t == initial_top(&main_arena)) return 0; + + switch(check_action) { + case 1: + fprintf(stderr, "malloc: top chunk is corrupt\n"); + break; + case 2: + abort(); + } + /* Try to set up a new top chunk. */ + brk = MORECORE(0); + front_misalign = (unsigned long)chunk2mem(brk) & MALLOC_ALIGN_MASK; + if (front_misalign > 0) + front_misalign = MALLOC_ALIGNMENT - front_misalign; + sbrk_size = front_misalign + top_pad + MINSIZE; + sbrk_size += pagesz - ((unsigned long)(brk + sbrk_size) & (pagesz - 1)); + new_brk = (char*)(MORECORE (sbrk_size)); + if (new_brk == (char*)(MORECORE_FAILURE)) return -1; + sbrked_mem = (new_brk - sbrk_base) + sbrk_size; + + top(&main_arena) = (mchunkptr)(brk + front_misalign); + set_head(top(&main_arena), (sbrk_size - front_misalign) | PREV_INUSE); + + return 0; +} + static Void_t* #if __STD_C malloc_check(size_t sz, const Void_t *caller) @@ -4202,16 +4292,10 @@ malloc_check(sz, caller) size_t sz; const Void_t *caller; INTERNAL_SIZE_T nb = request2size(sz + 1); (void)mutex_lock(&main_arena.mutex); - victim = chunk_alloc(&main_arena, nb); + victim = (top_check() >= 0) ? chunk_alloc(&main_arena, nb) : NULL; (void)mutex_unlock(&main_arena.mutex); if(!victim) return NULL; - nb = chunksize(victim); - if(chunk_is_mmapped(victim)) - --nb; - else - nb += SIZE_SZ - 1; - *((unsigned char*)victim + nb) = MAGICBYTE(victim); - return chunk2mem(victim); + return chunk2mem_check(victim, sz); } static void @@ -4290,7 +4374,7 @@ realloc_check(oldmem, bytes, caller) if(oldsize - SIZE_SZ >= nb) newp = oldp; /* do nothing */ else { /* Must alloc, copy, free. */ - newp = chunk_alloc(&main_arena, nb); + newp = (top_check() >= 0) ? chunk_alloc(&main_arena, nb) : NULL; if (newp) { MALLOC_COPY(chunk2mem(newp), oldmem, oldsize - 2*SIZE_SZ); munmap_chunk(oldp); @@ -4301,7 +4385,8 @@ realloc_check(oldmem, bytes, caller) #endif } else { #endif /* HAVE_MMAP */ - newp = chunk_realloc(&main_arena, oldp, oldsize, nb); + newp = (top_check() >= 0) ? + chunk_realloc(&main_arena, oldp, oldsize, nb) : NULL; #if 0 /* Erase freed memory. */ nb = chunksize(newp); if(oldp<newp || oldp>=chunk_at_offset(newp, nb)) { @@ -4317,13 +4402,7 @@ realloc_check(oldmem, bytes, caller) (void)mutex_unlock(&main_arena.mutex); if(!newp) return NULL; - nb = chunksize(newp); - if(chunk_is_mmapped(newp)) - --nb; - else - nb += SIZE_SZ - 1; - *((unsigned char*)newp + nb) = MAGICBYTE(newp); - return chunk2mem(newp); + return chunk2mem_check(newp, bytes); } static Void_t* @@ -4342,16 +4421,10 @@ memalign_check(alignment, bytes, caller) nb = request2size(bytes+1); (void)mutex_lock(&main_arena.mutex); - p = chunk_align(&main_arena, nb, alignment); + p = (top_check() >= 0) ? chunk_align(&main_arena, nb, alignment) : NULL; (void)mutex_unlock(&main_arena.mutex); if(!p) return NULL; - nb = chunksize(p); - if(chunk_is_mmapped(p)) - --nb; - else - nb += SIZE_SZ - 1; - *((unsigned char*)p + nb) = MAGICBYTE(p); - return chunk2mem(p); + return chunk2mem_check(p, bytes); } /* The following hooks are used when the global initialization in |