Unfortunately I had no time in the past days to continue with the exercises. We continue with the decompilation of the KeReadyThread function in Windows 7.
The following listing shows the disassembly:
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| nt!KeReadyThread:
828a8125 8bff mov edi,edi
828a8127 56 push esi
828a8128 8bf0 mov esi,eax
828a812a 8b4650 mov eax,dword ptr [esi+50h]
828a812d 8b4874 mov ecx,dword ptr [eax+74h]
828a8130 f6c107 test cl,7
828a8133 7409 je nt!KeReadyThread+0x19 (828a813e)
nt!KeReadyThread+0x10:
828a8135 e8b74af8ff call nt!KiInSwapSingleProcess (8282cbf1)
828a813a 84c0 test al,al
828a813c 7505 jne nt!KeReadyThread+0x1e (828a8143)
nt!KeReadyThread+0x19:
828a813e e892ef0000 call nt!KiFastReadyThread (828b70d5)
nt!KeReadyThread+0x1e:
828a8143 5e pop esi
828a8144 c3 ret
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According to this source, it has the following prototype:
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| VOID
KeReadyThread (
__inout PKTHREAD Thread
)
|
So, the function KeReadyThread takes one parameter, but does not reference it with the ebp register and the last instruction is a simple RET. The PKTHREAD structure is given below:
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| 0: kd> dt nt!_kthread
+0x000 Header : _DISPATCHER_HEADER
+0x010 CycleTime : Uint8B
+0x018 HighCycleTime : Uint4B
+0x020 QuantumTarget : Uint8B
+0x028 InitialStack : Ptr32 Void
+0x02c StackLimit : Ptr32 Void
+0x030 KernelStack : Ptr32 Void
+0x034 ThreadLock : Uint4B
+0x038 WaitRegister : _KWAIT_STATUS_REGISTER
+0x039 Running : UChar
+0x03a Alerted : [2] UChar
+0x03c KernelStackResident : Pos 0, 1 Bit
+0x03c ReadyTransition : Pos 1, 1 Bit
+0x03c ProcessReadyQueue : Pos 2, 1 Bit
+0x03c WaitNext : Pos 3, 1 Bit
+0x03c SystemAffinityActive : Pos 4, 1 Bit
+0x03c Alertable : Pos 5, 1 Bit
+0x03c GdiFlushActive : Pos 6, 1 Bit
+0x03c UserStackWalkActive : Pos 7, 1 Bit
+0x03c ApcInterruptRequest : Pos 8, 1 Bit
+0x03c ForceDeferSchedule : Pos 9, 1 Bit
+0x03c QuantumEndMigrate : Pos 10, 1 Bit
+0x03c UmsDirectedSwitchEnable : Pos 11, 1 Bit
+0x03c TimerActive : Pos 12, 1 Bit
+0x03c SystemThread : Pos 13, 1 Bit
+0x03c Reserved : Pos 14, 18 Bits
+0x03c MiscFlags : Int4B
+0x040 ApcState : _KAPC_STATE
+0x040 ApcStateFill : [23] UChar
+0x057 Priority : Char
+0x058 NextProcessor : Uint4B
+0x05c DeferredProcessor : Uint4B
+0x060 ApcQueueLock : Uint4B
+0x064 ContextSwitches : Uint4B
+0x068 State : UChar
+0x069 NpxState : Char
+0x06a WaitIrql : UChar
+0x06b WaitMode : Char
+0x06c WaitStatus : Int4B
+0x070 WaitBlockList : Ptr32 _KWAIT_BLOCK
+0x074 WaitListEntry : _LIST_ENTRY
+0x074 SwapListEntry : _SINGLE_LIST_ENTRY
+0x07c Queue : Ptr32 _KQUEUE
+0x080 WaitTime : Uint4B
+0x084 KernelApcDisable : Int2B
+0x086 SpecialApcDisable : Int2B
+0x084 CombinedApcDisable : Uint4B
+0x088 Teb : Ptr32 Void
+0x090 Timer : _KTIMER
+0x0b8 AutoAlignment : Pos 0, 1 Bit
+0x0b8 DisableBoost : Pos 1, 1 Bit
+0x0b8 EtwStackTraceApc1Inserted : Pos 2, 1 Bit
+0x0b8 EtwStackTraceApc2Inserted : Pos 3, 1 Bit
+0x0b8 CalloutActive : Pos 4, 1 Bit
+0x0b8 ApcQueueable : Pos 5, 1 Bit
+0x0b8 EnableStackSwap : Pos 6, 1 Bit
+0x0b8 GuiThread : Pos 7, 1 Bit
+0x0b8 UmsPerformingSyscall : Pos 8, 1 Bit
+0x0b8 VdmSafe : Pos 9, 1 Bit
+0x0b8 UmsDispatched : Pos 10, 1 Bit
+0x0b8 ReservedFlags : Pos 11, 21 Bits
+0x0b8 ThreadFlags : Int4B
+0x0bc ServiceTable : Ptr32 Void
+0x0c0 WaitBlock : [4] _KWAIT_BLOCK
+0x120 QueueListEntry : _LIST_ENTRY
+0x128 TrapFrame : Ptr32 _KTRAP_FRAME
+0x12c FirstArgument : Ptr32 Void
+0x130 CallbackStack : Ptr32 Void
+0x130 CallbackDepth : Uint4B
+0x134 ApcStateIndex : UChar
+0x135 BasePriority : Char
+0x136 PriorityDecrement : Char
+0x136 ForegroundBoost : Pos 0, 4 Bits
+0x136 UnusualBoost : Pos 4, 4 Bits
+0x137 Preempted : UChar
+0x138 AdjustReason : UChar
+0x139 AdjustIncrement : Char
+0x13a PreviousMode : Char
+0x13b Saturation : Char
+0x13c SystemCallNumber : Uint4B
+0x140 FreezeCount : Uint4B
+0x144 UserAffinity : _GROUP_AFFINITY
+0x150 Process : Ptr32 _KPROCESS
+0x154 Affinity : _GROUP_AFFINITY
+0x160 IdealProcessor : Uint4B
+0x164 UserIdealProcessor : Uint4B
+0x168 ApcStatePointer : [2] Ptr32 _KAPC_STATE
+0x170 SavedApcState : _KAPC_STATE
+0x170 SavedApcStateFill : [23] UChar
+0x187 WaitReason : UChar
+0x188 SuspendCount : Char
+0x189 Spare1 : Char
+0x18a OtherPlatformFill : UChar
+0x18c Win32Thread : Ptr32 Void
+0x190 StackBase : Ptr32 Void
+0x194 SuspendApc : _KAPC
+0x194 SuspendApcFill0 : [1] UChar
+0x195 ResourceIndex : UChar
+0x194 SuspendApcFill1 : [3] UChar
+0x197 QuantumReset : UChar
+0x194 SuspendApcFill2 : [4] UChar
+0x198 KernelTime : Uint4B
+0x194 SuspendApcFill3 : [36] UChar
+0x1b8 WaitPrcb : Ptr32 _KPRCB
+0x194 SuspendApcFill4 : [40] UChar
+0x1bc LegoData : Ptr32 Void
+0x194 SuspendApcFill5 : [47] UChar
+0x1c3 LargeStack : UChar
+0x1c4 UserTime : Uint4B
+0x1c8 SuspendSemaphore : _KSEMAPHORE
+0x1c8 SuspendSemaphorefill : [20] UChar
+0x1dc SListFaultCount : Uint4B
+0x1e0 ThreadListEntry : _LIST_ENTRY
+0x1e8 MutantListHead : _LIST_ENTRY
+0x1f0 SListFaultAddress : Ptr32 Void
+0x1f4 ThreadCounters : Ptr32 _KTHREAD_COUNTERS
+0x1f8 XStateSave : Ptr32 _XSTATE_SAVE
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The following data structures _KAPC_STATE and _KPROCESS are referenced in the disassembly:
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| _KAPC_STATE:
kd> dt nt!_KAPC_STATE
+0x000 ApcListHead : [2] _LIST_ENTRY
+0x010 Process : Ptr32 _KPROCESS
+0x014 KernelApcInProgress : UChar
+0x015 KernelApcPending : UChar
+0x016 UserApcPending : UChar
_KPROCESS
kd> dt nt!_kprocess
+0x000 Header : _DISPATCHER_HEADER
+0x010 ProfileListHead : _LIST_ENTRY
+0x018 DirectoryTableBase : Uint4B
+0x01c LdtDescriptor : _KGDTENTRY
+0x024 Int21Descriptor : _KIDTENTRY
+0x02c ThreadListHead : _LIST_ENTRY
+0x034 ProcessLock : Uint4B
+0x038 Affinity : _KAFFINITY_EX
+0x044 ReadyListHead : _LIST_ENTRY
+0x04c SwapListEntry : _SINGLE_LIST_ENTRY
+0x050 ActiveProcessors : _KAFFINITY_EX
+0x05c AutoAlignment : Pos 0, 1 Bit
+0x05c DisableBoost : Pos 1, 1 Bit
+0x05c DisableQuantum : Pos 2, 1 Bit
+0x05c ActiveGroupsMask : Pos 3, 1 Bit
+0x05c ReservedFlags : Pos 4, 28 Bits
+0x05c ProcessFlags : Int4B
+0x060 BasePriority : Char
+0x061 QuantumReset : Char
+0x062 Visited : UChar
+0x063 Unused3 : UChar
+0x064 ThreadSeed : [1] Uint4B
+0x068 IdealNode : [1] Uint2B
+0x06a IdealGlobalNode : Uint2B
+0x06c Flags : _KEXECUTE_OPTIONS
+0x06d Unused1 : UChar
+0x06e IopmOffset : Uint2B
+0x070 Unused4 : Uint4B
+0x074 StackCount : _KSTACK_COUNT
+0x078 ProcessListEntry : _LIST_ENTRY
+0x080 CycleTime : Uint8B
+0x088 KernelTime : Uint4B
+0x08c UserTime : Uint4B
+0x090 VdmTrapcHandler : Ptr32 Void
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Translation of the function to C:
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| VOID KeReadyThread (__inout PKTHREAD Thread)
{
if (Thread->ApcState.Process->StackCount != 7) {
KiFastReadythread(Thread);
}
else {
if (KiInSwapSingleProcess(Thread) == 0) {
KiFastReadythread(Thread);
}
}
}
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The if-structure can be changed as follows:
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| VOID KeReadyThread (__inout PKTHREAD Thread)
{
if (Thread->ApcState.Process->StackCount == 7) {
if (KiInSwapSingleProcess(Thread) != 0) {
return;
}
}
KiFastReadythread(Thread);
}
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