[PATCH 2/3] ntdll: Implement __fastfail().

[Jinoh Kang]

__fastfail() is used by the Visual C++ runtime and Windows system
libraries to signal that the in-process state is corrupted and
unrecoverable.

If __fastfail() is invoked, the NT kernel raises a second-chance
non-continuable exception STATUS_STACK_BUFFER_OVERRUN.  This quickly
terminates the process, bypassing all in-process exception handlers
(since they all rely on the potentially corrupted process state).

Signed-off-by: Jinoh Kang <jinoh.kang.kr at gmail.com>
---
 dlls/ntdll/unix/signal_arm.c    | 14 ++++++++++++--
 dlls/ntdll/unix/signal_arm64.c  | 11 +++++++++++
 dlls/ntdll/unix/signal_i386.c   |  9 ++++++++-
 dlls/ntdll/unix/signal_x86_64.c |  7 +++++++
 4 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/dlls/ntdll/unix/signal_arm.c b/dlls/ntdll/unix/signal_arm.c
index dbc2770f72e..1816e210644 100644
--- a/dlls/ntdll/unix/signal_arm.c
+++ b/dlls/ntdll/unix/signal_arm.c
@@ -809,13 +809,23 @@ static void segv_handler( int signal, siginfo_t *siginfo, void *sigcontext )
     switch (get_trap_code(signal, context))
     {
     case TRAP_ARM_PRIVINFLT:   /* Invalid opcode exception */
-        if (*(WORD *)PC_sig(context) == 0xdefe)  /* breakpoint */
+        switch (*(WORD *)PC_sig(context))
         {
+        case 0xdefb:  /* __fastfail */
+            rec.ExceptionCode = STATUS_STACK_BUFFER_OVERRUN;
+            rec.ExceptionFlags = EH_NONCONTINUABLE;
+            rec.NumberParameters = 1;
+            rec.ExceptionInformation[0] = REGn_sig(0, context);
+            setup_exception( context, &rec, FALSE );
+            return;
+        case 0xdefe:  /* breakpoint */
             rec.ExceptionCode = EXCEPTION_BREAKPOINT;
             rec.NumberParameters = 1;
             break;
+        default:
+            rec.ExceptionCode = EXCEPTION_ILLEGAL_INSTRUCTION;
+            break;
         }
-        rec.ExceptionCode = EXCEPTION_ILLEGAL_INSTRUCTION;
         break;
     case TRAP_ARM_PAGEFLT:  /* Page fault */
         rec.NumberParameters = 2;
diff --git a/dlls/ntdll/unix/signal_arm64.c b/dlls/ntdll/unix/signal_arm64.c
index ef70d4df44b..fe80732c03d 100644
--- a/dlls/ntdll/unix/signal_arm64.c
+++ b/dlls/ntdll/unix/signal_arm64.c
@@ -905,6 +905,17 @@ static void bus_handler( int signal, siginfo_t *siginfo, void *sigcontext )
 static void trap_handler( int signal, siginfo_t *siginfo, void *sigcontext )
 {
     EXCEPTION_RECORD rec = { 0 };
+    ucontext_t *context = sigcontext;
+
+    if ((get_fault_esr( context ) & 0xfe00ffffU) == 0xf200f003U)
+    {
+        rec.ExceptionCode = STATUS_STACK_BUFFER_OVERRUN;
+        rec.ExceptionFlags = EH_NONCONTINUABLE;
+        rec.NumberParameters = 1;
+        rec.ExceptionInformation[0] = REGn_sig( 0, context );
+        setup_exception( sigcontext, &rec, FALSE );
+        return;
+    }
 
     switch (siginfo->si_code)
     {
diff --git a/dlls/ntdll/unix/signal_i386.c b/dlls/ntdll/unix/signal_i386.c
index 1986c4728bf..6d448b99223 100644
--- a/dlls/ntdll/unix/signal_i386.c
+++ b/dlls/ntdll/unix/signal_i386.c
@@ -1489,7 +1489,7 @@ static void setup_exception( ucontext_t *sigcontext, EXCEPTION_RECORD *rec )
     struct xcontext xcontext;
     void *stack = setup_exception_record( sigcontext, rec, &xcontext );
 
-    setup_raise_exception( sigcontext, stack, rec, &xcontext );
+    setup_raise_exception( sigcontext, stack, rec, &xcontext, TRUE );
 }
 
 /* stack layout when calling an user apc function.
@@ -1660,6 +1660,13 @@ static BOOL handle_interrupt( unsigned int interrupt, ucontext_t *sigcontext, vo
 
     switch(interrupt)
     {
+    case 0x29:
+        rec->ExceptionCode = STATUS_STACK_BUFFER_OVERRUN;
+        rec->ExceptionFlags = EH_NONCONTINUABLE;
+        rec->NumberParameters = 1;
+        rec->ExceptionInformation[0] = context->Ecx;
+        setup_raise_exception( sigcontext, stack, rec, xcontext, FALSE );
+        return TRUE;
     case 0x2d:
         if (!is_wow64)
         {
diff --git a/dlls/ntdll/unix/signal_x86_64.c b/dlls/ntdll/unix/signal_x86_64.c
index ff4a40c7933..39bf1bcc835 100644
--- a/dlls/ntdll/unix/signal_x86_64.c
+++ b/dlls/ntdll/unix/signal_x86_64.c
@@ -2441,6 +2441,13 @@ static inline BOOL handle_interrupt( ucontext_t *sigcontext, EXCEPTION_RECORD *r
 
     switch (ERROR_sig(sigcontext) >> 3)
     {
+    case 0x29:
+        rec->ExceptionCode = STATUS_STACK_BUFFER_OVERRUN;
+        rec->ExceptionFlags = EH_NONCONTINUABLE;
+        rec->NumberParameters = 1;
+        rec->ExceptionInformation[0] = context->Rcx;
+        setup_raise_exception( sigcontext, rec, xcontext, FALSE );
+        return TRUE;
     case 0x2c:
         rec->ExceptionCode = STATUS_ASSERTION_FAILURE;
         break;
-- 
2.31.1