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Fixed bounded memblock iteration including negative-sized regions

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max 🍓
2023-01-09 18:25:35 +00:00
parent 2f6845692a
commit 34faa01b8e
1 changed files with 26 additions and 5 deletions
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31
sandbox/memblock/memblock.c
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@@ -271,6 +271,10 @@ void __next_memory_region(memblock_iter_t *it, memblock_type_t *type_a, memblock
for (; idx_a < type_a->count; idx_a++) {
memblock_region_t *m = &type_a->regions[idx_a];
uintptr_t m_start = m->base;
uintptr_t m_end = m->limit;
if (!type_b) {
it->it_base = m->base;
it->it_limit = m->limit;
@@ -280,9 +284,6 @@ void __next_memory_region(memblock_iter_t *it, memblock_type_t *type_a, memblock
return;
}
uintptr_t m_start = m->base;
uintptr_t m_end = m->limit;
if (m_end < start) {
/* we haven't reached the requested memory range yet */
continue;
@@ -300,9 +301,24 @@ void __next_memory_region(memblock_iter_t *it, memblock_type_t *type_a, memblock
* if we have gone past the last reserved region, these variables delimit the range between the end
* of the last reserved region and the end of memory. */
uintptr_t r_start = idx_b > 0 ? r[-1].limit + 1 : 0;
uintptr_t r_end = idx_b < type_b->count ? r->base : ADDR_MAX;
uintptr_t r_end;
if (r_start == r_end) {
if (idx_b < type_b->count) {
r_end = r->base;
/* we decrement r_end to get the address of the last byte of the free region.
if r_end is already zero, there is a reserved region starting at address 0x0.
as long as r_end == r_start == 0x00000, we will skip this region. */
if (r_end) {
r_end--;
}
} else {
/* this maximum value will be clamped to the bounds of memblock.memory
before being returned to the caller */
r_end = ADDR_MAX;
}
if (r_start >= r_end) {
/* this free region has a length of zero, move to the next one */
continue;
}
@@ -329,6 +345,11 @@ void __next_memory_region(memblock_iter_t *it, memblock_type_t *type_a, memblock
it->it_base = MAX(it->it_base, start);
it->it_limit = MIN(it->it_limit, end);
if (it->it_limit <= it->it_base) {
/* this region is not part of the specified bounds, skip it. */
continue;
}
it->it_status = MEMBLOCK_MEMORY;
/* whichever region is smaller, increment the pointer for that type, so we can