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b87070f98c
realloc(ptr, 0) is equivalent to free(ptr). It may return NULL, in which
case vector_do_shrink_to_fit() won't update the vector's data and
capacity. A subsequent append will then try to reuse the previous
allocation, causing a use-after-free. free() empty vectors explicitly
instead.
Fixes: 8d52536271 ("libdrgn: add common vector implementation")
Signed-off-by: Omar Sandoval <osandov@osandov.com>
67 lines
1.5 KiB
C
67 lines
1.5 KiB
C
// Copyright (c) Facebook, Inc. and its affiliates.
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// SPDX-License-Identifier: GPL-3.0+
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#include "vector.h"
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bool vector_do_reserve(size_t new_capacity, size_t entry_size, void **data,
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size_t *capacity)
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{
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size_t bytes;
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void *new_data;
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if (new_capacity <= *capacity || new_capacity == 0)
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return true;
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if (__builtin_mul_overflow(new_capacity, entry_size, &bytes))
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return false;
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new_data = realloc(*data, bytes);
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if (!new_data)
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return false;
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*data = new_data;
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*capacity = new_capacity;
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return true;
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}
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void vector_do_shrink_to_fit(size_t size, size_t entry_size, void **data,
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size_t *capacity)
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{
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if (*capacity > size) {
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if (size > 0) {
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/*
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* We already have at least size * entry_size bytes
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* allocated, so we don't need to worry about overflow.
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*/
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void *new_data = realloc(*data, size * entry_size);
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if (new_data) {
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*data = new_data;
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*capacity = size;
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}
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} else {
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free(*data);
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*data = NULL;
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*capacity = 0;
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}
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}
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}
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bool vector_reserve_for_append(size_t size, size_t entry_size, void **data,
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size_t *capacity)
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{
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size_t new_capacity, bytes;
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void *new_data;
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if (size < *capacity)
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return true;
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if (*capacity == 0)
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new_capacity = 1;
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else if (__builtin_mul_overflow(2U, *capacity, &new_capacity))
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return false;
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if (__builtin_mul_overflow(new_capacity, entry_size, &bytes))
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return false;
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new_data = realloc(*data, bytes);
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if (!new_data)
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return false;
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*data = new_data;
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*capacity = new_capacity;
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return true;
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}
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