ULONG
NTAPI
-KdpPrompt(IN LPSTR InString,
- IN USHORT InStringLength,
- OUT LPSTR OutString,
- IN USHORT OutStringLength)
+KdpPrompt(
+ _In_reads_bytes_(InStringLength) PCHAR UnsafeInString,
+ _In_ USHORT InStringLength,
+ _Out_writes_bytes_(OutStringLength) PCHAR UnsafeOutString,
+ _In_ USHORT OutStringLength,
+ _In_ KPROCESSOR_MODE PreviousMode)
{
USHORT i;
CHAR Response;
ULONG DummyScanCode;
KIRQL OldIrql;
+ PCHAR InString;
+ PCHAR OutString;
+
+ /* Normalize the lengths */
+ InStringLength = min(InStringLength,
+ 512);
+ OutStringLength = min(OutStringLength,
+ 512);
+
+ /* Check if we need to verify the string */
+ if (PreviousMode != KernelMode)
+ {
+ /* Handle user-mode buffers safely */
+ _SEH2_TRY
+ {
+ /* Probe the prompt */
+ ProbeForRead(UnsafeInString,
+ InStringLength,
+ 1);
+
+ /* Capture prompt */
+ InString = _alloca(InStringLength);
+ RtlCopyMemory(InString,
+ UnsafeInString,
+ InStringLength);
+
+ /* Probe and make room for response */
+ ProbeForWrite(UnsafeOutString,
+ OutStringLength,
+ 1);
+ OutString = _alloca(OutStringLength);
+ }
+ _SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
+ {
+ /* Bad string pointer, bail out */
+ _SEH2_YIELD(return 0);
+ }
+ _SEH2_END;
+ }
+ else
+ {
+ InString = UnsafeInString;
+ OutString = UnsafeOutString;
+ }
/* Acquire the printing spinlock without waiting at raised IRQL */
while (TRUE)
/* Lower IRQL back */
KeLowerIrql(OldIrql);
+ /* Copy back response if required */
+ if (PreviousMode != KernelMode)
+ {
+ _SEH2_TRY
+ {
+ /* Safely copy back response to user mode */
+ RtlCopyMemory(UnsafeOutString,
+ OutString,
+ i);
+ }
+ _SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
+ {
+ /* String became invalid after we exited, fail */
+ _SEH2_YIELD(return 0);
+ }
+ _SEH2_END;
+ }
+
/* Return the length */
return i;
}