[reactos] 06/19: [NTOS:KE:X64] Fix bugs in KeContextToTrapFrame and KeTrapFrameToContext

[Timo Kreuzer]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=fe6752f852ab1d8af90a7…

commit fe6752f852ab1d8af90a726092879273c31b4c15
Author:     Timo Kreuzer <timo.kreuzer(a)reactos.org>
AuthorDate: Mon Feb 12 19:21:50 2018 +0100
Commit:     Timo Kreuzer <timo.kreuzer(a)reactos.org>
CommitDate: Sat Oct 31 14:23:16 2020 +0100

    [NTOS:KE:X64] Fix bugs in KeContextToTrapFrame and KeTrapFrameToContext
    
    Set valid EFlags, the non-volatiles need to be taken from the exception frame, because
the ones from the trap frame might not be set.
---
 ntoskrnl/ke/amd64/context.c | 44 +++++++++++++++++++++++++++++++++-----------
 1 file changed, 33 insertions(+), 11 deletions(-)

diff --git a/ntoskrnl/ke/amd64/context.c b/ntoskrnl/ke/amd64/context.c
index 3e21cae3197..61c286cd69d 100644
--- a/ntoskrnl/ke/amd64/context.c
+++ b/ntoskrnl/ke/amd64/context.c
@@ -56,8 +56,7 @@ KeContextToTrapFrame(IN PCONTEXT Context,
     }
 
     /* Handle floating point registers */
-    if ((ContextFlags & CONTEXT_FLOATING_POINT) &&
-        ((Context->SegCs & MODE_MASK) != KernelMode))
+    if ((ContextFlags & CONTEXT_FLOATING_POINT))
     {
         TrapFrame->MxCsr = Context->MxCsr;
         TrapFrame->Xmm0 = Context->Xmm0;
@@ -84,24 +83,35 @@ KeContextToTrapFrame(IN PCONTEXT Context,
     /* Handle control registers */
     if (ContextFlags & CONTEXT_CONTROL)
     {
-        /* Check if this was a Kernel Trap */
+        /* RIP, RSP, EFLAGS */
+        TrapFrame->Rip = Context->Rip;
+        TrapFrame->Rsp = Context->Rsp;
+        TrapFrame->EFlags = Context->EFlags;
+
         if ((Context->SegCs & MODE_MASK) == KernelMode)
         {
             /* Set valid selectors */
             TrapFrame->SegCs = KGDT64_R0_CODE;
             TrapFrame->SegSs = KGDT64_R0_DATA;
+
+            /* Set valid EFLAGS */
+            TrapFrame->EFlags &= (EFLAGS_USER_SANITIZE | EFLAGS_INTERRUPT_MASK);
         }
         else
         {
             /* Copy selectors */
             TrapFrame->SegCs = Context->SegCs;
+            if (TrapFrame->SegCs != (KGDT64_R3_CODE | RPL_MASK))
+            {
+                TrapFrame->SegCs = (KGDT64_R3_CMCODE | RPL_MASK);
+            }
+
             TrapFrame->SegSs = Context->SegSs;
-        }
 
-        /* RIP, RSP, EFLAGS */
-        TrapFrame->Rip = Context->Rip;
-        TrapFrame->Rsp = Context->Rsp;
-        TrapFrame->EFlags = Context->EFlags;
+            /* Set valid EFLAGS */
+            TrapFrame->EFlags &= EFLAGS_USER_SANITIZE;
+            TrapFrame->EFlags |= EFLAGS_INTERRUPT_MASK;
+        }
     }
 
     /* Handle segment selectors */
@@ -136,6 +146,18 @@ KeContextToTrapFrame(IN PCONTEXT Context,
         TrapFrame->Dr3 = Context->Dr3;
         TrapFrame->Dr6 = Context->Dr6;
         TrapFrame->Dr7 = Context->Dr7;
+
+        if ((Context->SegCs & MODE_MASK) != KernelMode)
+        {
+            if (TrapFrame->Dr0 > (ULONG64)MmHighestUserAddress)
+                TrapFrame->Dr0 = 0;
+            if (TrapFrame->Dr1 > (ULONG64)MmHighestUserAddress)
+                TrapFrame->Dr1 = 0;
+            if (TrapFrame->Dr2 > (ULONG64)MmHighestUserAddress)
+                TrapFrame->Dr2 = 0;
+            if (TrapFrame->Dr3 > (ULONG64)MmHighestUserAddress)
+                TrapFrame->Dr3 = 0;
+        }
     }
 
     /* Restore IRQL */
@@ -164,11 +186,8 @@ KeTrapFrameToContext(IN PKTRAP_FRAME TrapFrame,
     if (ContextFlags & CONTEXT_INTEGER)
     {
         Context->Rax = TrapFrame->Rax;
-        Context->Rbx = TrapFrame->Rbx;
         Context->Rcx = TrapFrame->Rcx;
         Context->Rdx = TrapFrame->Rdx;
-        Context->Rsi = TrapFrame->Rsi;
-        Context->Rdi = TrapFrame->Rdi;
         Context->Rbp = TrapFrame->Rbp;
         Context->R8 = TrapFrame->R8;
         Context->R9 = TrapFrame->R9;
@@ -177,6 +196,9 @@ KeTrapFrameToContext(IN PKTRAP_FRAME TrapFrame,
 
         if (ExceptionFrame)
         {
+            Context->Rbx = ExceptionFrame->Rbx;
+            Context->Rsi = ExceptionFrame->Rsi;
+            Context->Rdi = ExceptionFrame->Rdi;
             Context->R12 = ExceptionFrame->R12;
             Context->R13 = ExceptionFrame->R13;
             Context->R14 = ExceptionFrame->R14;