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Fix junk/zero filling for realloc(). Junk filling was missing in one case,

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and zero filling was broken in a way that could cause memory corruption.

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This commit is contained in:
jasone 2007-06-15 22:00:16 +00:00
parent 11712476cc
commit a3eda1cfc4
1 changed files with 48 additions and 36 deletions
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84
lib/libc/stdlib/malloc.c
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@ -1,5 +1,5 @@
/*-
* Copyright (C) 2006 Jason Evans <jasone@FreeBSD.org>.
* Copyright (C) 2006,2007 Jason Evans <jasone@FreeBSD.org>.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@ -47,36 +47,37 @@
* categories according to size class. Assuming runtime defaults, 4 kB pages
* and a 16 byte quantum, the size classes in each category are as follows:
*
* |====================================|
* | Category | Subcategory | Size |
* |====================================|
* | Small | Tiny | 2 |
* | | | 4 |
* | | | 8 |
* | |----------------+--------|
* | | Quantum-spaced | 16 |
* | | | 32 |
* | | | 48 |
* | | | ... |
* | | | 480 |
* | | | 496 |
* | | | 512 |
* | |----------------+--------|
* | | Sub-page | 1 kB |
* | | | 2 kB |
* |====================================|
* | Large | 4 kB |
* | | 8 kB |
* | | 16 kB |
* | | ... |
* | | 256 kB |
* | | 512 kB |
* |====================================|
* | Huge | 1 MB |
* | | 2 MB |
* | | 3 MB |
* | | ... |
* |====================================|
* |=====================================|
* | Category | Subcategory | Size |
* |=====================================|
* | Small | Tiny | 2 |
* | | | 4 |
* | | | 8 |
* | |----------------+---------|
* | | Quantum-spaced | 16 |
* | | | 32 |
* | | | 48 |
* | | | ... |
* | | | 480 |
* | | | 496 |
* | | | 512 |
* | |----------------+---------|
* | | Sub-page | 1 kB |
* | | | 2 kB |
* |=====================================|
* | Large | 4 kB |
* | | 8 kB |
* | | 12 kB |
* | | ... |
* | | 1012 kB |
* | | 1016 kB |
* | | 1020 kB |
* |=====================================|
* | Huge | 1 MB |
* | | 2 MB |
* | | 3 MB |
* | | ... |
* |=====================================|
*
* A different mechanism is used for each category:
*
@ -1419,7 +1420,7 @@ chunk_dealloc(void *chunk, size_t size)
/*
* Choose an arena based on a per-thread value (fast-path code, calls slow-path
* code if necessary.
* code if necessary).
*/
static inline arena_t *
choose_arena(void)
@ -1438,7 +1439,7 @@ choose_arena(void)
* app switches to threaded mode, the initial thread may end up
* being assigned to some other arena, but this one-time switch
* shouldn't cause significant issues.
* */
*/
return (arenas[0]);
}
@ -1898,7 +1899,9 @@ arena_run_alloc(arena_t *arena, size_t size)
}
}
/* No usable runs. Allocate a new chunk, then try again. */
/*
* No usable runs. Create a new chunk from which to allocate the run.
*/
chunk = arena_chunk_alloc(arena);
if (chunk == NULL)
return (NULL);
@ -2401,6 +2404,7 @@ arena_ralloc(void *ptr, size_t size, size_t oldsize)
if (ret == NULL)
return (NULL);
/* Junk/zero-filling were already done by arena_malloc(). */
if (size < oldsize)
memcpy(ret, ptr, size);
else
@ -2411,7 +2415,7 @@ IN_PLACE:
if (opt_junk && size < oldsize)
memset((void *)((uintptr_t)ptr + size), 0x5a, oldsize - size);
else if (opt_zero && size > oldsize)
memset((void *)((uintptr_t)ptr + size), 0, oldsize - size);
memset((void *)((uintptr_t)ptr + oldsize), 0, size - oldsize);
return (ptr);
}
@ -2757,8 +2761,16 @@ huge_ralloc(void *ptr, size_t size, size_t oldsize)
/* Avoid moving the allocation if the size class would not change. */
if (oldsize > arena_maxclass &&
CHUNK_CEILING(size) == CHUNK_CEILING(oldsize))
CHUNK_CEILING(size) == CHUNK_CEILING(oldsize)) {
if (opt_junk && size < oldsize) {
memset((void *)((uintptr_t)ptr + size), 0x5a, oldsize
- size);
} else if (opt_zero && size > oldsize) {
memset((void *)((uintptr_t)ptr + oldsize), 0, size
- oldsize);
}
return (ptr);
}
/*
* If we get here, then size and oldsize are different enough that we