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CHERI: address_space_core should bound more

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When reserving with leftover space, bound both the reservation and the residual
pointer.  This may be excessive?
This commit is contained in:
Nathaniel Wesley Filardo
2021-11-11 14:43:16 +00:00
committed by Nathaniel Wesley Filardo
parent 9b60e8256d
commit 13a4b0471e
1 changed files with 16 additions and 4 deletions
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20
src/backend/address_space_core.h
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@@ -232,7 +232,13 @@ namespace snmalloc
size_t length_align_bits = (bits::BITS - 1) - bits::clz(length);
size_t align_bits = bits::min(base_align_bits, length_align_bits);
size_t align = bits::one_at_bit(align_bits);
auto b = base.as_static<FreeChunk>();
/*
* Now that we have found a maximally-aligned block, we can set bounds
* and be certain that we won't hit representation imprecision.
*/
auto b =
Aal::capptr_bound<FreeChunk, capptr::bounds::Chunk>(base, align);
check_block(b, align_bits);
add_block<PAL, Pagemap>(local_state, align_bits, b);
@@ -289,7 +295,7 @@ namespace snmalloc
* of the block is retained by the address space manager.
*
* This is useful for allowing the space required for alignment to be
* used, by smaller objects.
* used by smaller objects.
*/
template<
SNMALLOC_CONCEPT(ConceptPAL) PAL,
@@ -309,8 +315,14 @@ namespace snmalloc
{
if (rsize > size)
{
add_range<PAL, Pagemap>(
local_state, pointer_offset(res, size), rsize - size);
/*
* Set bounds on the allocation requested but leave the residual with
* wider bounds for the moment; we'll fix that above in add_range.
*/
size_t residual_size = rsize - size;
auto residual = pointer_offset(res, size);
res = Aal::capptr_bound<void, capptr::bounds::Chunk>(res, size);
add_range<PAL, Pagemap>(local_state, residual, residual_size);
}
}
return res;