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[NTOSKRNL] Fix our-of-bounds access and memory leak (CID-1401178, 1401177) in FsRtlIsDbcsInExpression

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This commit is contained in:
Timo Kreuzer 2017-10-11 14:20:57 +02:00
parent d310df0dd2
commit 561f18afea
1 changed files with 37 additions and 15 deletions
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52
ntoskrnl/fsrtl/dbcsname.c
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@ -163,6 +163,8 @@ FsRtlIsDbcsInExpression(IN PANSI_STRING Expression,
USHORT Offset, Position, BackTrackingPosition, OldBackTrackingPosition;
USHORT BackTrackingBuffer[16], OldBackTrackingBuffer[16] = {0};
PUSHORT BackTrackingSwap, BackTracking = BackTrackingBuffer, OldBackTracking = OldBackTrackingBuffer;
ULONG BackTrackingBufferSize = RTL_NUMBER_OF(BackTrackingBuffer);
PVOID AllocatedBuffer = NULL;
USHORT ExpressionPosition, NamePosition = 0, MatchingChars = 1;
USHORT NameChar = 0, ExpressionChar;
BOOLEAN EndOfName = FALSE;
@ -281,22 +283,40 @@ FsRtlIsDbcsInExpression(IN PANSI_STRING Expression,
}
/* If buffer too small */
if (BackTrackingPosition > RTL_NUMBER_OF(BackTrackingBuffer) - 1)
if (BackTrackingPosition > BackTrackingBufferSize - 2)
{
/* Allocate memory for BackTracking */
BackTracking = ExAllocatePoolWithTag(PagedPool | POOL_RAISE_IF_ALLOCATION_FAILURE,
(Expression->Length + 1) * sizeof(USHORT) * 2,
'nrSF');
/* Copy old buffer content */
/* We should only ever get here once! */
ASSERT(AllocatedBuffer == NULL);
ASSERT((BackTracking == BackTrackingBuffer) || (BackTracking == OldBackTrackingBuffer));
ASSERT((OldBackTracking == BackTrackingBuffer) || (OldBackTracking == OldBackTrackingBuffer));
/* Calculate buffer size */
BackTrackingBufferSize = (Expression->Length + 1) * 2;
/* Allocate memory for both back-tracking buffers */
AllocatedBuffer = ExAllocatePoolWithTag(PagedPool | POOL_RAISE_IF_ALLOCATION_FAILURE,
2 * BackTrackingBufferSize * sizeof(USHORT),
'nrSF');
if (AllocatedBuffer == NULL)
{
DPRINT1("Failed to allocate BackTracking buffer. BackTrackingBufferSize = =x%lx\n",
BackTrackingBufferSize);
Result = FALSE;
goto Exit;
}
/* Backtracking is at the start of the buffer */
BackTracking = AllocatedBuffer;
/* Copy BackTrackingBuffer content */
RtlCopyMemory(BackTracking,
BackTrackingBuffer,
RTL_NUMBER_OF(BackTrackingBuffer) * sizeof(USHORT));
/* Allocate memory for OldBackTracking */
OldBackTracking = ExAllocatePoolWithTag(PagedPool | POOL_RAISE_IF_ALLOCATION_FAILURE,
(Expression->Length + 1) * sizeof(USHORT) * 2,
'nrSF');
/* Copy old buffer content */
/* OldBackTracking is after BackTracking */
OldBackTracking = &BackTracking[BackTrackingBufferSize];
/* Copy OldBackTrackingBuffer content */
RtlCopyMemory(OldBackTracking,
OldBackTrackingBuffer,
RTL_NUMBER_OF(OldBackTrackingBuffer) * sizeof(USHORT));
@ -404,11 +424,13 @@ FsRtlIsDbcsInExpression(IN PANSI_STRING Expression,
/* Store result value */
Result = (OldBackTracking[MatchingChars - 1] == Expression->Length * 2);
Exit:
/* Frees the memory if necessary */
if (BackTracking != BackTrackingBuffer && BackTracking != OldBackTrackingBuffer)
ExFreePoolWithTag(BackTracking, 'nrSF');
if (OldBackTracking != BackTrackingBuffer && OldBackTracking != OldBackTrackingBuffer)
ExFreePoolWithTag(OldBackTracking, 'nrSF');
if (AllocatedBuffer != NULL)
{
ExFreePoolWithTag(AllocatedBuffer, 'nrSF');
}
return Result;
}