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LibC: Fix crash in free() now that mprotect() works correctly

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After we mprotect(PROT_NONE) an allocation block, we can't expect to
read the m_size from that block right after. :^)
This commit is contained in:
Andreas Kling 2020-03-06 10:52:36 +01:00
parent 2709116334
commit 52954ccce6
1 changed files with 3 additions and 2 deletions
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5
Libraries/LibC/malloc.cpp
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@ -303,11 +303,12 @@ static void free_impl(void* ptr)
if (auto* allocator = big_allocator_for_size(block->m_size)) {
if (allocator->blocks.size() < number_of_big_blocks_to_keep_around_per_size_class) {
allocator->blocks.append(block);
if (mprotect(block, block->m_size, PROT_NONE) < 0) {
size_t this_block_size = block->m_size;
if (mprotect(block, this_block_size, PROT_NONE) < 0) {
perror("mprotect");
ASSERT_NOT_REACHED();
}
if (madvise(block, block->m_size, MADV_SET_VOLATILE) != 0) {
if (madvise(block, this_block_size, MADV_SET_VOLATILE) != 0) {
perror("madvise");
ASSERT_NOT_REACHED();
}