ntoskrnl.exe: Make IoAllocateIrp not crash on negative values.

[Bernhard Übelacker]

https://bugs.winehq.org/show_bug.cgi?id=39734

Changes should avoid crash in acedrv11.sys.
IoAllocateIrp is called with a stack_size of -128.

Tested against Windows XP.
(See the test based on wine-staging "driver testing framework".)

Signed-off-by: Bernhard Übelacker <bernhardu at vr-web.de>
---
 dlls/ntoskrnl.exe/ntoskrnl.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/dlls/ntoskrnl.exe/ntoskrnl.c b/dlls/ntoskrnl.exe/ntoskrnl.c
index 36488a7..f2ccc61 100644
--- a/dlls/ntoskrnl.exe/ntoskrnl.c
+++ b/dlls/ntoskrnl.exe/ntoskrnl.c
@@ -592,15 +592,20 @@ PIRP WINAPI IoAllocateIrp( CCHAR stack_size, BOOLEAN charge_quota )
 {
     SIZE_T size;
     PIRP irp;
+    CCHAR _stack_size = stack_size;
 
     TRACE( "%d, %d\n", stack_size, charge_quota );
 
-    size = sizeof(IRP) + stack_size * sizeof(IO_STACK_LOCATION);
+    if (_stack_size <= 0 || (_stack_size > 1 && stack_size < 8))
+        _stack_size = 8;
+
+    size = sizeof(IRP) + _stack_size * sizeof(IO_STACK_LOCATION);
     irp = ExAllocatePool( NonPagedPool, size );
     if (irp == NULL)
         return NULL;
     IoInitializeIrp( irp, size, stack_size );
-    irp->AllocationFlags = IRP_ALLOCATED_FIXED_SIZE;
+    if (stack_size >= 1 && stack_size <= 8)
+        irp->AllocationFlags = IRP_ALLOCATED_FIXED_SIZE;
     if (charge_quota)
         irp->AllocationFlags |= IRP_LOOKASIDE_ALLOCATION;
     return irp;
-- 
2.1.4