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malloc: refactored aligned_OK and misaligned_chunk

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Renamed aligned_OK to misaligned_mem as to be similar
to misaligned_chunk, and reversed any assertions using
the macro.  Made misaligned_chunk call misaligned_mem after
chunk2mem rather than bitmasking with the malloc alignment
itself, since misaligned_chunk is meant to test the data
chunk itself rather than the header, and the compiler
will optimise the addition so the ternary operator is not
needed.

Reviewed-by: Wilco Dijkstra  <Wilco.Dijkstra@arm.com>
This commit is contained in:
William Hunt
2025-06-25 11:35:05 +00:00
committed by Wilco Dijkstra
parent 53ea6db9fd
commit d1ad959b00
2 changed files with 10 additions and 12 deletions
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20
malloc/malloc.c
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@ -1309,11 +1309,9 @@ nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/* Check if m has acceptable alignment */
#define aligned_OK(m) (((unsigned long)(m) & MALLOC_ALIGN_MASK) == 0)
#define misaligned_mem(m) ((uintptr_t)(m) & MALLOC_ALIGN_MASK)
#define misaligned_chunk(p) \
((uintptr_t)(MALLOC_ALIGNMENT == CHUNK_HDR_SZ ? (p) : chunk2mem (p)) \
& MALLOC_ALIGN_MASK)
#define misaligned_chunk(p) (misaligned_mem( chunk2mem (p)))
/* pad request bytes into a usable size -- internal version */
/* Note: This must be a macro that evaluates to a compile time constant
@ -2103,7 +2101,7 @@ do_check_chunk (mstate av, mchunkptr p)
/* chunk is page-aligned */
assert (((prev_size (p) + sz) & (GLRO (dl_pagesize) - 1)) == 0);
/* mem is aligned */
assert (aligned_OK (chunk2mem (p)));
assert (!misaligned_chunk (p));
}
}
@ -2127,7 +2125,7 @@ do_check_free_chunk (mstate av, mchunkptr p)
if ((unsigned long) (sz) >= MINSIZE)
{
assert ((sz & MALLOC_ALIGN_MASK) == 0);
assert (aligned_OK (chunk2mem (p)));
assert (!misaligned_chunk (p));
/* ... matching footer field */
assert (prev_size (next_chunk (p)) == sz);
/* ... and is fully consolidated */
@ -2206,7 +2204,7 @@ do_check_remalloced_chunk (mstate av, mchunkptr p, INTERNAL_SIZE_T s)
assert ((sz & MALLOC_ALIGN_MASK) == 0);
assert ((unsigned long) (sz) >= MINSIZE);
/* ... and alignment */
assert (aligned_OK (chunk2mem (p)));
assert (!misaligned_chunk (p));
/* chunk is less than MINSIZE more than request */
assert ((long) (sz) - (long) (s) >= 0);
assert ((long) (sz) - (long) (s + MINSIZE) < 0);
@ -3094,7 +3092,7 @@ mremap_chunk (mchunkptr p, size_t new_size)
p = (mchunkptr) (cp + offset);
assert (aligned_OK (chunk2mem (p)));
assert (!misaligned_chunk (p));
assert (prev_size (p) == offset);
set_head (p, (new_size - offset) | IS_MMAPPED);
@ -3207,7 +3205,7 @@ tcache_get_n (size_t tc_idx, tcache_entry **ep, bool mangled)
else
e = REVEAL_PTR (*ep);
if (__glibc_unlikely (!aligned_OK (e)))
if (__glibc_unlikely (misaligned_mem (e)))
malloc_printerr ("malloc(): unaligned tcache chunk detected");
void *ne = e == NULL ? NULL : REVEAL_PTR (e->next);
@ -3331,7 +3329,7 @@ tcache_double_free_verify (tcache_entry *e)
{
if (cnt >= mp_.tcache_count)
malloc_printerr ("free(): too many chunks detected in tcache");
if (__glibc_unlikely (!aligned_OK (tmp)))
if (__glibc_unlikely (misaligned_mem (tmp)))
malloc_printerr ("free(): unaligned chunk detected in tcache 2");
if (tmp == e)
malloc_printerr ("free(): double free detected in tcache 2");
@ -3365,7 +3363,7 @@ tcache_thread_shutdown (void)
while (tcache_tmp->entries[i])
{
tcache_entry *e = tcache_tmp->entries[i];
if (__glibc_unlikely (!aligned_OK (e)))
if (__glibc_unlikely (misaligned_mem (e)))
malloc_printerr ("tcache_thread_shutdown(): "
"unaligned tcache chunk detected");
tcache_tmp->entries[i] = REVEAL_PTR (e->next);