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Free unused trampoline regions on abort and attach error #17

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Free unused trampoline regions on abort and attach error #17

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4 changes: 4 additions & 0 deletions Source/SlimDetours/SlimDetours.inl
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Original file line number Diff line number Diff line change
Expand Up @@ -266,6 +266,10 @@ detour_free_trampoline(

VOID detour_free_unused_trampoline_regions(VOID);

VOID
detour_free_trampoline_region_if_unused(
_In_ PDETOUR_TRAMPOLINE pTrampoline);

BYTE
detour_align_from_trampoline(
_In_ PDETOUR_TRAMPOLINE pTrampoline,
Expand Down
47 changes: 39 additions & 8 deletions Source/SlimDetours/Trampoline.c
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Expand Up @@ -400,24 +400,29 @@ detour_is_region_empty(
return TRUE;
}

static
VOID
detour_free_unused_trampoline_regions(VOID)
detour_free_region(
_In_ PDETOUR_REGION* ppRegionBase,
_In_ PDETOUR_REGION pRegion)
{
PVOID pMem;
SIZE_T sMem;
*ppRegionBase = pRegion->pNext;
PVOID pMem = pRegion;
SIZE_T sMem = 0;
NtFreeVirtualMemory(NtCurrentProcess(), &pMem, &sMem, MEM_RELEASE);
}

VOID
detour_free_unused_trampoline_regions(VOID)
{
PDETOUR_REGION* ppRegionBase = &s_pRegions;
PDETOUR_REGION pRegion = s_pRegions;

while (pRegion != NULL)
{
if (detour_is_region_empty(pRegion))
{
*ppRegionBase = pRegion->pNext;

pMem = pRegion;
sMem = 0;
NtFreeVirtualMemory(NtCurrentProcess(), &pMem, &sMem, MEM_RELEASE);
detour_free_region(ppRegionBase, pRegion);
s_pRegion = NULL;
} else
{
Expand All @@ -427,6 +432,32 @@ detour_free_unused_trampoline_regions(VOID)
}
}

VOID
detour_free_trampoline_region_if_unused(
_In_ PDETOUR_TRAMPOLINE pTrampoline)
{
PDETOUR_REGION pTargetRegion = (PDETOUR_REGION)((ULONG_PTR)pTrampoline & ~(ULONG_PTR)0xffff);

PDETOUR_REGION* ppRegionBase = &s_pRegions;
PDETOUR_REGION pRegion = s_pRegions;

while (pRegion != NULL)
{
if (pRegion == pTargetRegion)
{
if (detour_is_region_empty(pRegion))
{
detour_free_region(ppRegionBase, pRegion);
s_pRegion = NULL;
}
break;
}

ppRegionBase = &pRegion->pNext;
pRegion = *ppRegionBase;
}
}

BYTE
detour_align_from_trampoline(
_In_ PDETOUR_TRAMPOLINE pTrampoline,
Expand Down
7 changes: 7 additions & 0 deletions Source/SlimDetours/Transaction.c
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Original file line number Diff line number Diff line change
Expand Up @@ -98,6 +98,7 @@ SlimDetoursTransactionAbort(VOID)
PVOID pMem;
SIZE_T sMem;
DWORD dwOld;
BOOL freed = FALSE;

if (s_nPendingThreadId != NtCurrentThreadId())
{
Expand All @@ -115,13 +116,18 @@ SlimDetoursTransactionAbort(VOID)
{
detour_free_trampoline(o->pTrampoline);
o->pTrampoline = NULL;
freed = TRUE;
}

PDETOUR_OPERATION n = o->pNext;
detour_memory_free(o);
o = n;
}
s_pPendingOperations = NULL;
if (freed)
{
detour_free_unused_trampoline_regions();
}

// Make sure the trampoline pages are no longer writable.
detour_runnable_trampoline_regions();
Expand Down Expand Up @@ -324,6 +330,7 @@ SlimDetoursAttach(
if (pTrampoline != NULL)
{
detour_free_trampoline(pTrampoline);
detour_free_trampoline_region_if_unused(pTrampoline);
pTrampoline = NULL;
}
if (o != NULL)
Expand Down