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[NTOS:MM] Fix placing entries into MmNonPagedPoolFreeListHead

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When freeing pages, free page entries with pages num == 3 were
incorrectly treated as entries with pages num >= 4 and thus
their re-insertion was not triggered. That lead to non paged pool
fragmentation (can be triggered by kmtest:ExPools, for example)

Also, altered the index acquisition code for MmNonPagedPoolFreeList
entries so it looks more clear
This commit is contained in:
Victor Perevertkin 2021-06-14 04:50:01 +03:00 committed by Jérôme Gardou
parent a3cadf630a
commit 3f601122bc
1 changed files with 6 additions and 10 deletions
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16
ntoskrnl/mm/ARM3/pool.c
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@ -680,8 +680,7 @@ MiAllocatePoolPages(IN POOL_TYPE PoolType,
//
// Allocations of less than 4 pages go into their individual buckets
//
i = SizeInPages - 1;
if (i >= MI_MAX_FREE_PAGE_LISTS) i = MI_MAX_FREE_PAGE_LISTS - 1;
i = min(SizeInPages, MI_MAX_FREE_PAGE_LISTS) - 1;
//
// Loop through all the free page lists based on the page index
@ -738,8 +737,7 @@ MiAllocatePoolPages(IN POOL_TYPE PoolType,
if (FreeEntry->Size != 0)
{
/* Check which list to insert this entry into */
i = FreeEntry->Size - 1;
if (i >= MI_MAX_FREE_PAGE_LISTS) i = MI_MAX_FREE_PAGE_LISTS - 1;
i = min(FreeEntry->Size, MI_MAX_FREE_PAGE_LISTS) - 1;
/* Insert the entry into the free list head, check for prot. pool */
if (MmProtectFreedNonPagedPool)
@ -1176,11 +1174,11 @@ MiFreePoolPages(IN PVOID StartingVa)
}
//
// Check if the entry is small enough to be indexed on a free list
// Check if the entry is small enough (1-3 pages) to be indexed on a free list
// If it is, we'll want to re-insert it, since we're about to
// collapse our pages on top of it, which will change its count
//
if (FreeEntry->Size < (MI_MAX_FREE_PAGE_LISTS - 1))
if (FreeEntry->Size < MI_MAX_FREE_PAGE_LISTS)
{
/* Remove the item from the list, depending if pool is protected */
if (MmProtectFreedNonPagedPool)
@ -1196,8 +1194,7 @@ MiFreePoolPages(IN PVOID StartingVa)
//
// And now find the new appropriate list to place it in
//
i = (ULONG)(FreeEntry->Size - 1);
if (i >= MI_MAX_FREE_PAGE_LISTS) i = MI_MAX_FREE_PAGE_LISTS - 1;
i = min(FreeEntry->Size, MI_MAX_FREE_PAGE_LISTS) - 1;
/* Insert the entry into the free list head, check for prot. pool */
if (MmProtectFreedNonPagedPool)
@ -1228,8 +1225,7 @@ MiFreePoolPages(IN PVOID StartingVa)
//
// Find the appropriate list we should be on
//
i = FreeEntry->Size - 1;
if (i >= MI_MAX_FREE_PAGE_LISTS) i = MI_MAX_FREE_PAGE_LISTS - 1;
i = min(FreeEntry->Size, MI_MAX_FREE_PAGE_LISTS) - 1;
/* Insert the entry into the free list head, check for prot. pool */
if (MmProtectFreedNonPagedPool)