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Convert alloc paths to capptr::Alloc<void>

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The use of void* had let an overzealous unsafe_ptr() leak a pointer with address
space control to the client (in LocalAllocator::alloc_not_small, specifically).
Correct this to call capptr_chunk_is_alloc() (to capture our intent) and
capptr_to_user_address_control() (to do the bounding) and defer the conversion
to void* until the very periphery of the allocator, using capptr_reveal()
(again, to capture intent).
This commit is contained in:
Nathaniel Wesley Filardo
2021-10-20 02:49:32 +01:00
committed by Nathaniel Wesley Filardo
parent 31b8d99ca6
commit 5bb556cb68
3 changed files with 19 additions and 20 deletions
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15
src/mem/corealloc.h
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@@ -176,7 +176,7 @@ namespace snmalloc
* - Allocating stub in the message queue
* Note this is not performance critical as very infrequently called.
*/
void* small_alloc_one(size_t size)
capptr::Alloc<void> small_alloc_one(size_t size)
{
SNMALLOC_ASSERT(attached_cache != nullptr);
auto domesticate =
@@ -285,7 +285,8 @@ namespace snmalloc
[local_state](freelist::QueuePtr p) SNMALLOC_FAST_PATH_LAMBDA {
return capptr_domesticate<SharedStateHandle>(local_state, p);
};
void* p = finish_alloc_no_zero(fl.take(key, domesticate), sizeclass);
capptr::Alloc<void> p =
finish_alloc_no_zero(fl.take(key, domesticate), sizeclass);
#ifdef SNMALLOC_CHECK_CLIENT
// Check free list is well-formed on platforms with
@@ -321,11 +322,11 @@ namespace snmalloc
auto start_of_slab = pointer_align_down<void>(
p, snmalloc::sizeclass_to_slab_size(sizeclass));
// TODO Add bounds correctly here
chunk_record->chunk = capptr::Chunk<void>(start_of_slab);
chunk_record->chunk = capptr::Chunk<void>(start_of_slab.unsafe_ptr());
#ifdef SNMALLOC_TRACING
std::cout << "Slab " << start_of_slab << " is unused, Object sizeclass "
<< sizeclass << std::endl;
std::cout << "Slab " << start_of_slab.unsafe_ptr()
<< " is unused, Object sizeclass " << sizeclass << std::endl;
#endif
return chunk_record;
}
@@ -654,7 +655,7 @@ namespace snmalloc
}
template<ZeroMem zero_mem>
SNMALLOC_SLOW_PATH void*
SNMALLOC_SLOW_PATH capptr::Alloc<void>
small_alloc(sizeclass_t sizeclass, freelist::Iter<>& fast_free_list)
{
size_t rsize = sizeclass_to_size(sizeclass);
@@ -716,7 +717,7 @@ namespace snmalloc
}
template<ZeroMem zero_mem>
SNMALLOC_SLOW_PATH void* small_alloc_slow(
SNMALLOC_SLOW_PATH capptr::Alloc<void> small_alloc_slow(
sizeclass_t sizeclass, freelist::Iter<>& fast_free_list, size_t rsize)
{
// No existing free list get a new slab.