Alexandre Julliard : ntdll: Support delayed freeing of heap blocks to catch use-after-free bugs.
Module: wine Branch: master Commit: b7b8929f0b72dc63d61e96e3eaca177da79f5865 URL: http://source.winehq.org/git/wine.git/?a=commit;h=b7b8929f0b72dc63d61e96e3ea... Author: Alexandre Julliard <julliard(a)winehq.org> Date: Thu Jan 28 19:43:38 2010 +0100 ntdll: Support delayed freeing of heap blocks to catch use-after-free bugs. --- dlls/ntdll/heap.c | 82 +++++++++++++++++++++++++++++++++++++++++++++++------ 1 files changed, 73 insertions(+), 9 deletions(-) diff --git a/dlls/ntdll/heap.c b/dlls/ntdll/heap.c index 07fec3f..622b174 100644 --- a/dlls/ntdll/heap.c +++ b/dlls/ntdll/heap.c @@ -82,6 +82,7 @@ typedef struct /* Value for arena 'magic' field */ #define ARENA_INUSE_MAGIC 0x455355 +#define ARENA_PENDING_MAGIC 0xbedead #define ARENA_FREE_MAGIC 0x45455246 #define ARENA_LARGE_MAGIC 0x6752614c @@ -151,6 +152,8 @@ typedef struct tagHEAP struct list large_list; /* Large blocks list */ SIZE_T grow_size; /* Size of next subheap for growing heap */ DWORD magic; /* Magic number */ + DWORD pending_pos; /* Position in pending free requests ring */ + ARENA_INUSE **pending_free; /* Ring buffer for pending free requests */ RTL_CRITICAL_SECTION critSection; /* Critical section for serialization */ FREE_LIST_ENTRY *freeList; /* Free lists */ } HEAP; @@ -159,6 +162,7 @@ typedef struct tagHEAP #define HEAP_DEF_SIZE 0x110000 /* Default heap size = 1Mb + 64Kb */ #define COMMIT_MASK 0xffff /* bitmask for commit/decommit granularity */ +#define MAX_FREE_PENDING 1024 /* max number of free requests to delay */ /* some undocumented flags (names are made up) */ #define HEAP_PAGE_ALLOCS 0x01000000 @@ -275,7 +279,8 @@ static void subheap_notify_free_all(SUBHEAP const *subheap) else { ARENA_INUSE const *pArena = (ARENA_INUSE const *)ptr; - if (pArena->magic!=ARENA_INUSE_MAGIC) ERR("bad inuse_magic @%p\n", pArena); + if (pArena->magic != ARENA_INUSE_MAGIC && pArena->magic != ARENA_PENDING_MAGIC) + ERR("bad inuse_magic @%p\n", pArena); notify_free(pArena + 1); ptr += sizeof(*pArena) + (pArena->size & ARENA_SIZE_MASK); } @@ -362,7 +367,9 @@ static void HEAP_Dump( HEAP *heap ) else { ARENA_INUSE *pArena = (ARENA_INUSE *)ptr; - DPRINTF( "%p %08x used %08x\n", pArena, pArena->magic, pArena->size & ARENA_SIZE_MASK ); + DPRINTF( "%p %08x %s %08x\n", + pArena, pArena->magic, pArena->magic == ARENA_INUSE_MAGIC ? "used" : "pend", + pArena->size & ARENA_SIZE_MASK ); ptr += sizeof(*pArena) + (pArena->size & ARENA_SIZE_MASK); arenaSize += sizeof(ARENA_INUSE); usedSize += pArena->size & ARENA_SIZE_MASK; @@ -607,11 +614,25 @@ static void HEAP_CreateFreeBlock( SUBHEAP *subheap, void *ptr, SIZE_T size ) */ static void HEAP_MakeInUseBlockFree( SUBHEAP *subheap, ARENA_INUSE *pArena ) { + HEAP *heap = subheap->heap; ARENA_FREE *pFree; - SIZE_T size = (pArena->size & ARENA_SIZE_MASK) + sizeof(*pArena); + SIZE_T size; + + if (heap->pending_free) + { + ARENA_INUSE *prev = heap->pending_free[heap->pending_pos]; + heap->pending_free[heap->pending_pos] = pArena; + heap->pending_pos = (heap->pending_pos + 1) % MAX_FREE_PENDING; + pArena->magic = ARENA_PENDING_MAGIC; + mark_block_free( pArena + 1, pArena->size & ARENA_SIZE_MASK, heap->flags ); + if (!prev) return; + pArena = prev; + subheap = HEAP_FindSubHeap( heap, pArena ); + } /* Check if we can merge with previous block */ + size = (pArena->size & ARENA_SIZE_MASK) + sizeof(*pArena); if (pArena->size & ARENA_FLAG_PREV_FREE) { pFree = *((ARENA_FREE **)pArena - 1); @@ -1168,7 +1189,7 @@ static BOOL HEAP_ValidateInUseArena( const SUBHEAP *subheap, const ARENA_INUSE * } /* Check magic number */ - if (pArena->magic != ARENA_INUSE_MAGIC) + if (pArena->magic != ARENA_INUSE_MAGIC && pArena->magic != ARENA_PENDING_MAGIC) { if (quiet == NOISY) { ERR("Heap %p: invalid in-use arena magic %08x for %p\n", subheap->heap, pArena->magic, pArena ); @@ -1238,7 +1259,24 @@ static BOOL HEAP_ValidateInUseArena( const SUBHEAP *subheap, const ARENA_INUSE * return FALSE; } /* Check unused bytes */ - if (flags & HEAP_TAIL_CHECKING_ENABLED) + if (pArena->magic == ARENA_PENDING_MAGIC) + { + DWORD *ptr = (DWORD *)(pArena + 1); + DWORD *end = (DWORD *)((char *)ptr + size); + + while (ptr < end) + { + if (*ptr != ARENA_FREE_FILLER) + { + ERR("Heap %p: free block %p overwritten at %p by %08x\n", + subheap->heap, (ARENA_INUSE *)pArena + 1, ptr, *ptr ); + if (!*ptr) { HEAP_Dump( subheap->heap ); DbgBreakPoint(); } + return FALSE; + } + ptr++; + } + } + else if (flags & HEAP_TAIL_CHECKING_ENABLED) { const unsigned char *data = (const unsigned char *)(pArena + 1) + size - pArena->unused_bytes; @@ -1366,6 +1404,8 @@ static BOOL validate_block_pointer( HEAP *heap, SUBHEAP **ret_subheap, const ARE ret = HEAP_ValidateInUseArena( subheap, arena, QUIET ); else if ((ULONG_PTR)arena % ALIGNMENT != ARENA_OFFSET) WARN( "Heap %p: unaligned arena pointer %p\n", subheap->heap, arena ); + else if (arena->magic == ARENA_PENDING_MAGIC) + WARN( "Heap %p: block %p used after free\n", subheap->heap, arena + 1 ); else if (arena->magic != ARENA_INUSE_MAGIC) WARN( "Heap %p: invalid in-use arena magic %08x for %p\n", subheap->heap, arena->magic, arena ); else if (arena->size & ARENA_FLAG_FREE) @@ -1435,8 +1475,11 @@ void heap_set_debug_flags( HANDLE handle ) } else { - mark_block_tail( (char *)(arena + 1) + size - arena->unused_bytes, - arena->unused_bytes, flags ); + if (arena->magic == ARENA_PENDING_MAGIC) + mark_block_free( arena + 1, size, flags ); + else + mark_block_tail( (char *)(arena + 1) + size - arena->unused_bytes, + arena->unused_bytes, flags ); ptr += sizeof(ARENA_INUSE) + size; } } @@ -1446,6 +1489,19 @@ void heap_set_debug_flags( HANDLE handle ) mark_block_tail( (char *)(large + 1) + large->data_size, large->block_size - sizeof(*large) - large->data_size, flags ); } + + if ((heap->flags & HEAP_GROWABLE) && !heap->pending_free && + ((flags & HEAP_FREE_CHECKING_ENABLED) || RUNNING_ON_VALGRIND)) + { + void *ptr = NULL; + SIZE_T size = MAX_FREE_PENDING * sizeof(*heap->pending_free); + + if (!NtAllocateVirtualMemory( NtCurrentProcess(), &ptr, 4, &size, MEM_COMMIT, PAGE_READWRITE )) + { + heap->pending_free = ptr; + heap->pending_pos = 0; + } + } } @@ -1550,6 +1606,12 @@ HANDLE WINAPI RtlDestroyHeap( HANDLE heap ) NtFreeVirtualMemory( NtCurrentProcess(), &addr, &size, MEM_RELEASE ); } subheap_notify_free_all(&heapPtr->subheap); + if (heapPtr->pending_free) + { + size = 0; + addr = heapPtr->pending_free; + NtFreeVirtualMemory( NtCurrentProcess(), &addr, &size, MEM_RELEASE ); + } size = 0; addr = heapPtr->subheap.base; NtFreeVirtualMemory( NtCurrentProcess(), &addr, &size, MEM_RELEASE ); @@ -2052,7 +2114,8 @@ NTSTATUS WINAPI RtlWalkHeap( HANDLE heap, PVOID entry_ptr ) goto HW_end; } - if (((ARENA_INUSE *)ptr - 1)->magic == ARENA_INUSE_MAGIC) + if (((ARENA_INUSE *)ptr - 1)->magic == ARENA_INUSE_MAGIC || + ((ARENA_INUSE *)ptr - 1)->magic == ARENA_PENDING_MAGIC) { ARENA_INUSE *pArena = (ARENA_INUSE *)ptr - 1; ptr += pArena->size & ARENA_SIZE_MASK; @@ -2100,7 +2163,8 @@ NTSTATUS WINAPI RtlWalkHeap( HANDLE heap, PVOID entry_ptr ) entry->lpData = pArena + 1; entry->cbData = pArena->size & ARENA_SIZE_MASK; entry->cbOverhead = sizeof(ARENA_INUSE); - entry->wFlags = PROCESS_HEAP_ENTRY_BUSY; + entry->wFlags = (pArena->magic == ARENA_PENDING_MAGIC) ? + PROCESS_HEAP_UNCOMMITTED_RANGE : PROCESS_HEAP_ENTRY_BUSY; /* FIXME: can't handle PROCESS_HEAP_ENTRY_MOVEABLE and PROCESS_HEAP_ENTRY_DDESHARE yet */ }
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Alexandre Julliard