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[NTOS:MM] Improve MmCanFileBeTruncated

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This commit is contained in:
Jérôme Gardou 2021-01-27 16:28:45 +01:00
parent 3e43aa1305
commit 91a4e62376
1 changed files with 12 additions and 30 deletions
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42
ntoskrnl/mm/section.c
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@ -4077,54 +4077,36 @@ BOOLEAN NTAPI
MmCanFileBeTruncated (IN PSECTION_OBJECT_POINTERS SectionObjectPointer,
IN PLARGE_INTEGER NewFileSize)
{
KIRQL OldIrql = MiAcquirePfnLock();
BOOLEAN Ret;
PMM_SECTION_SEGMENT Segment;
CheckSectionPointer:
/* Check whether an ImageSectionObject exists */
if (SectionObjectPointer->ImageSectionObject != NULL)
{
DPRINT1("ERROR: File can't be truncated because it has an image section\n");
MiReleasePfnLock(OldIrql);
return FALSE;
}
Segment = (PMM_SECTION_SEGMENT)SectionObjectPointer->DataSectionObject;
/* Wait for it to be created/deleted properly */
while (Segment && (Segment->SegFlags & (MM_SEGMENT_INCREATE | MM_SEGMENT_INDELETE)))
Segment = MiGrabDataSection(SectionObjectPointer);
if (!Segment)
{
LARGE_INTEGER ShortTime;
ShortTime.QuadPart = -10 * 100 * 1000;
/* Bad luck. Wait a bit for the operation to finish */
MiReleasePfnLock(OldIrql);
KeDelayExecutionThread(KernelMode, FALSE, &ShortTime);
OldIrql = MiAcquirePfnLock();
goto CheckSectionPointer;
/* There is no data section. It's fine to do anything. */
return TRUE;
}
if (Segment)
MmLockSectionSegment(Segment);
if ((Segment->SectionCount == 1) && (SectionObjectPointer->SharedCacheMap != NULL))
{
if ((Segment->SectionCount == 1) && (SectionObjectPointer->SharedCacheMap != NULL))
{
/* If the cache is the only one holding a reference to the segment, then it's fine to resize */
Ret = TRUE;
}
else
{
/* We can't shrink, but we can extend */
Ret = NewFileSize->QuadPart >= Segment->RawLength.QuadPart;
}
/* If the cache is the only one holding a reference to the segment, then it's fine to resize */
Ret = TRUE;
}
else
{
Ret = TRUE;
/* We can't shrink, but we can extend */
Ret = NewFileSize->QuadPart >= Segment->RawLength.QuadPart;
}
MiReleasePfnLock(OldIrql);
MmUnlockSectionSegment(Segment);
MmDereferenceSegment(Segment);
DPRINT("FIXME: didn't check for outstanding write probes\n");