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Add checks for deallocation with size (#160)

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Ensure that the size deallocated with is the correct size. If the size
supplied is wrong, then internal invariants can break.
This commit is contained in:
Matthew Parkinson
2020-04-02 07:04:52 +01:00
committed by GitHub
parent 06eef5c4c5
commit 7bb00a7169
1 changed files with 31 additions and 0 deletions
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31
src/mem/alloc.h
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@@ -199,6 +199,35 @@ namespace snmalloc
#endif
}
/**
* Checks the allocation at `p` could have been validly allocated with
* a size of `size`.
*/
void check_size(void* p, size_t size)
{
#if defined(CHECK_CLIENT)
auto asize = alloc_size(p);
auto asc = size_to_sizeclass(asize);
if (size_to_sizeclass(size) != asc)
{
// Correction for large classes.
if (asc > NUM_SIZECLASSES)
{
if (bits::next_pow2(size) != asize)
error("Deallocating with incorrect size supplied.");
}
// Correction for zero sized allocations.
else if ((size != 0) && (asc != 0))
{
error("Deallocating with incorrect size supplied.");
}
}
#else
UNUSED(p);
UNUSED(size);
#endif
}
/*
* Free memory of a statically known size. Must be called with an
* external pointer.
@@ -210,6 +239,7 @@ namespace snmalloc
UNUSED(size);
return free(p);
#else
check_size(p, size);
constexpr sizeclass_t sizeclass = size_to_sizeclass_const(size);
if (sizeclass < NUM_SMALL_CLASSES)
@@ -249,6 +279,7 @@ namespace snmalloc
UNUSED(size);
return free(p);
#else
check_size(p, size);
if (likely((size - 1) <= (sizeclass_to_size(NUM_SMALL_CLASSES - 1) - 1)))
{
Superslab* super = Superslab::get(p);