diff options
Diffstat (limited to 'malloc/malloc.c')
| -rw-r--r-- | malloc/malloc.c | 58 |
1 files changed, 33 insertions, 25 deletions
diff --git a/malloc/malloc.c b/malloc/malloc.c index ebcf1ff960..7522da4c43 100644 --- a/malloc/malloc.c +++ b/malloc/malloc.c @@ -1286,18 +1286,26 @@ nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ headers have distinct tags. Converting fully from one to the other involves extracting the tag at the other address and creating a suitable pointer using it. That can be quite expensive. There are - many occasions, though when the pointer will not be dereferenced - (for example, because we only want to assert that the pointer is - correctly aligned). In these cases it is more efficient not - to extract the tag, since the answer will be the same either way. - chunk2rawmem() can be used in these cases. - */ + cases when the pointers are not dereferenced (for example only used + for alignment check) so the tags are not relevant, and there are + cases when user data is not tagged distinctly from malloc headers + (user data is untagged because tagging is done late in malloc and + early in free). User memory tagging across internal interfaces: + + sysmalloc: Returns untagged memory. + _int_malloc: Returns untagged memory. + _int_free: Takes untagged memory. + _int_memalign: Returns untagged memory. + _int_memalign: Returns untagged memory. + _mid_memalign: Returns tagged memory. + _int_realloc: Takes and returns tagged memory. +*/ /* The chunk header is two SIZE_SZ elements, but this is used widely, so we define it here for clarity later. */ #define CHUNK_HDR_SZ (2 * SIZE_SZ) -/* Convert a user mem pointer to a chunk address without correcting +/* Convert a chunk address to a user mem pointer without correcting the tag. */ #define chunk2rawmem(p) ((void*)((char*)(p) + CHUNK_HDR_SZ)) @@ -1320,7 +1328,7 @@ nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ #define aligned_OK(m) (((unsigned long)(m) & MALLOC_ALIGN_MASK) == 0) #define misaligned_chunk(p) \ - ((uintptr_t)(MALLOC_ALIGNMENT == CHUNK_HDR_SZ ? (p) : chunk2mem (p)) \ + ((uintptr_t)(MALLOC_ALIGNMENT == CHUNK_HDR_SZ ? (p) : chunk2rawmem (p)) \ & MALLOC_ALIGN_MASK) /* pad request bytes into a usable size -- internal version */ @@ -2528,7 +2536,7 @@ sysmalloc (INTERNAL_SIZE_T nb, mstate av) check_chunk (av, p); - return chunk2mem (p); + return chunk2rawmem (p); } } } @@ -2898,7 +2906,7 @@ sysmalloc (INTERNAL_SIZE_T nb, mstate av) set_head (p, nb | PREV_INUSE | (av != &main_arena ? NON_MAIN_ARENA : 0)); set_head (remainder, remainder_size | PREV_INUSE); check_malloced_chunk (av, p, nb); - return chunk2mem (p); + return chunk2rawmem (p); } /* catch all failure paths */ @@ -3030,7 +3038,7 @@ mremap_chunk (mchunkptr p, size_t new_size) assert (chunk_is_mmapped (p)); uintptr_t block = (uintptr_t) p - offset; - uintptr_t mem = (uintptr_t) chunk2mem(p); + uintptr_t mem = (uintptr_t) chunk2rawmem(p); size_t total_size = offset + size; if (__glibc_unlikely ((block | total_size) & (pagesize - 1)) != 0 || __glibc_unlikely (!powerof2 (mem & (pagesize - 1)))) @@ -3096,7 +3104,7 @@ static __thread tcache_perthread_struct *tcache = NULL; static __always_inline void tcache_put (mchunkptr chunk, size_t tc_idx) { - tcache_entry *e = (tcache_entry *) chunk2mem (chunk); + tcache_entry *e = (tcache_entry *) chunk2rawmem (chunk); /* Mark this chunk as "in the tcache" so the test in _int_free will detect a double free. */ @@ -3411,7 +3419,7 @@ __libc_realloc (void *oldmem, size_t bytes) newp = mremap_chunk (oldp, nb); if (newp) { - void *newmem = chunk2mem (newp); + void *newmem = tag_at (chunk2rawmem (newp)); /* Give the new block a different tag. This helps to ensure that stale handles to the previous mapping are not reused. There's a performance hit for both us and the @@ -3852,7 +3860,7 @@ _int_malloc (mstate av, size_t bytes) } } #endif - void *p = chunk2mem (victim); + void *p = chunk2rawmem (victim); alloc_perturb (p, bytes); return p; } @@ -3910,7 +3918,7 @@ _int_malloc (mstate av, size_t bytes) } } #endif - void *p = chunk2mem (victim); + void *p = chunk2rawmem (victim); alloc_perturb (p, bytes); return p; } @@ -4011,7 +4019,7 @@ _int_malloc (mstate av, size_t bytes) set_foot (remainder, remainder_size); check_malloced_chunk (av, victim, nb); - void *p = chunk2mem (victim); + void *p = chunk2rawmem (victim); alloc_perturb (p, bytes); return p; } @@ -4043,7 +4051,7 @@ _int_malloc (mstate av, size_t bytes) { #endif check_malloced_chunk (av, victim, nb); - void *p = chunk2mem (victim); + void *p = chunk2rawmem (victim); alloc_perturb (p, bytes); return p; #if USE_TCACHE @@ -4205,7 +4213,7 @@ _int_malloc (mstate av, size_t bytes) set_foot (remainder, remainder_size); } check_malloced_chunk (av, victim, nb); - void *p = chunk2mem (victim); + void *p = chunk2rawmem (victim); alloc_perturb (p, bytes); return p; } @@ -4313,7 +4321,7 @@ _int_malloc (mstate av, size_t bytes) set_foot (remainder, remainder_size); } check_malloced_chunk (av, victim, nb); - void *p = chunk2mem (victim); + void *p = chunk2rawmem (victim); alloc_perturb (p, bytes); return p; } @@ -4351,7 +4359,7 @@ _int_malloc (mstate av, size_t bytes) set_head (remainder, remainder_size | PREV_INUSE); check_malloced_chunk (av, victim, nb); - void *p = chunk2mem (victim); + void *p = chunk2rawmem (victim); alloc_perturb (p, bytes); return p; } @@ -4419,7 +4427,7 @@ _int_free (mstate av, mchunkptr p, int have_lock) if (tcache != NULL && tc_idx < mp_.tcache_bins) { /* Check to see if it's already in the tcache. */ - tcache_entry *e = (tcache_entry *) chunk2mem (p); + tcache_entry *e = (tcache_entry *) chunk2rawmem (p); /* This test succeeds on double free. However, we don't 100% trust it (it also matches random payload data at a 1 in @@ -4491,7 +4499,7 @@ _int_free (mstate av, mchunkptr p, int have_lock) malloc_printerr ("free(): invalid next size (fast)"); } - free_perturb (chunk2mem(p), size - CHUNK_HDR_SZ); + free_perturb (chunk2rawmem(p), size - CHUNK_HDR_SZ); atomic_store_relaxed (&av->have_fastchunks, true); unsigned int idx = fastbin_index(size); @@ -4564,7 +4572,7 @@ _int_free (mstate av, mchunkptr p, int have_lock) || __builtin_expect (nextsize >= av->system_mem, 0)) malloc_printerr ("free(): invalid next size (normal)"); - free_perturb (chunk2mem(p), size - CHUNK_HDR_SZ); + free_perturb (chunk2rawmem(p), size - CHUNK_HDR_SZ); /* consolidate backward */ if (!prev_inuse(p)) { @@ -4964,7 +4972,7 @@ _int_memalign (mstate av, size_t alignment, size_t bytes) { set_prev_size (newp, prev_size (p) + leadsize); set_head (newp, newsize | IS_MMAPPED); - return chunk2mem (newp); + return chunk2rawmem (newp); } /* Otherwise, give back leader, use the rest */ @@ -4995,7 +5003,7 @@ _int_memalign (mstate av, size_t alignment, size_t bytes) } check_inuse_chunk (av, p); - return chunk2mem (p); + return chunk2rawmem (p); } |