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[NTOSKRNL] Rewrite IoCheckEaBufferValidity() so that it's less magic

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And make its coding style consistent with our rules
This commit is contained in:
Pierre Schweitzer 2018-10-27 21:54:55 +02:00
parent 43c78d4b75
commit 03294dd097
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GPG Key ID: 7545556C3D585B0B
1 changed files with 64 additions and 67 deletions
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131
ntoskrnl/io/iomgr/util.c
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@ -192,82 +192,79 @@ IoCheckEaBufferValidity(IN PFILE_FULL_EA_INFORMATION EaBuffer,
IN ULONG EaLength,
OUT PULONG ErrorOffset)
{
PFILE_FULL_EA_INFORMATION EaBufferEnd;
ULONG NextEaBufferOffset;
LONG IntEaLength;
ULONG NextEntryOffset;
UCHAR EaNameLength;
ULONG ComputedLength;
PFILE_FULL_EA_INFORMATION Current;
PAGED_CODE();
/* Length of the rest */
IntEaLength = EaLength;
EaBufferEnd = EaBuffer;
/* The rest length of the buffer */
while (IntEaLength >= FIELD_OFFSET(FILE_FULL_EA_INFORMATION, EaName[0]))
/* We will browse all the entries */
for (Current = EaBuffer; ; Current = (PFILE_FULL_EA_INFORMATION)((ULONG_PTR)Current + NextEntryOffset))
{
/*
* The rest of buffer must greater than
* sizeof(FILE_FULL_EA_INFORMATION) + buffer
*/
NextEaBufferOffset =
EaBufferEnd->EaNameLength + EaBufferEnd->EaValueLength +
FIELD_OFFSET(FILE_FULL_EA_INFORMATION, EaName[0]) + 1;
if ((ULONG)IntEaLength >= NextEaBufferOffset)
/* Check that we have enough bits left for the current entry */
if (EaLength < FIELD_OFFSET(FILE_FULL_EA_INFORMATION, EaName))
{
/* is the EaBufferName terminated with zero? */
if (EaBufferEnd->EaName[EaBufferEnd->EaNameLength]==0)
{
/* more EaBuffers ahead */
if (EaBufferEnd->NextEntryOffset == 0)
{
/* test the rest buffersize */
IntEaLength = IntEaLength - NextEaBufferOffset;
if (IntEaLength >= 0)
{
return STATUS_SUCCESS;
}
}
else
{
/*
* From MSDN:
* http://msdn2.microsoft.com/en-us/library/ms795740.aspx
* For all entries except the last one, the value of
* NextEntryOffset must be greater than zero and
* must fall on a ULONG boundary.
*/
NextEaBufferOffset = ((NextEaBufferOffset + 3) & ~3);
if ((EaBufferEnd->NextEntryOffset == NextEaBufferOffset) &&
((LONG)EaBufferEnd->NextEntryOffset > 0))
{
/*
* The rest of buffer must be greater
* than the following offset.
*/
IntEaLength =
IntEaLength - EaBufferEnd->NextEntryOffset;
if (IntEaLength >= 0)
{
EaBufferEnd = (PFILE_FULL_EA_INFORMATION)
((ULONG_PTR)EaBufferEnd +
EaBufferEnd->NextEntryOffset);
continue;
}
}
}
}
goto FailPath;
}
break;
EaNameLength = Current->EaNameLength;
ComputedLength = Current->EaValueLength + EaNameLength + FIELD_OFFSET(FILE_FULL_EA_INFORMATION, EaName) + 1;
/* Check that we have enough bits left for storing the name and its value */
if (EaLength < ComputedLength)
{
goto FailPath;
}
/* Make sure the name is null terminated */
if (Current->EaName[EaNameLength] != ANSI_NULL)
{
goto FailPath;
}
/* Get the next entry offset */
NextEntryOffset = Current->NextEntryOffset;
/* If it's 0, it's a termination case */
if (NextEntryOffset == 0)
{
/* If we don't overflow! */
if (EaLength - ComputedLength < 0)
{
goto FailPath;
}
break;
}
/* Compare the next offset we computed with the provided one, they must match */
if (ALIGN_UP_BY(ComputedLength, sizeof(ULONG)) != NextEntryOffset)
{
goto FailPath;
}
/* Check next entry offset value is positive */
if (NextEntryOffset < 0)
{
goto FailPath;
}
/* Compute the remaining bits */
EaLength -= NextEntryOffset;
/* We must have bits left */
if (EaLength < 0)
{
goto FailPath;
}
/* Move to the next entry */
}
if (ErrorOffset != NULL)
{
/* Calculate the error offset */
*ErrorOffset = (ULONG)((ULONG_PTR)EaBufferEnd - (ULONG_PTR)EaBuffer);
}
/* If we end here, everything went OK */
return STATUS_SUCCESS;
FailPath:
/* If we end here, we failed, set failed offset */
*ErrorOffset = (ULONG_PTR)Current - (ULONG_PTR)EaBuffer;
return STATUS_EA_LIST_INCONSISTENT;
}