ntdll: Implement __fastfail().

__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@gmail.com>

ntdll: Implement __fastfail().
c4c9a695 · Jinoh Kang · Alexandre Julliard · 7fbe8b8e · c4c9a695 · c4c9a695
Commit c4c9a695 authored Dec 05, 2021 by Jinoh Kang Committed by Alexandre Julliard May 31, 2022
5 changed files
--- a/dlls/ntdll/tests/exception.c
+++ b/dlls/ntdll/tests/exception.c
@@ -8466,7 +8466,6 @@ static void subtest_fastfail(unsigned int code)

    } while (de.dwDebugEventCode != EXIT_PROCESS_DEBUG_EVENT);

-    todo_wine
    ok(had_ff || broken(had_se) /* Win7 */, "fast fail did not occur\n");

    wait_child_process( pi.hProcess );

--- a/dlls/ntdll/unix/signal_arm.c
+++ b/dlls/ntdll/unix/signal_arm.c
@@ -812,13 +812,28 @@ 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 */
+        {
+            CONTEXT ctx;
+            save_context( &ctx, sigcontext );
+            rec.ExceptionCode = STATUS_STACK_BUFFER_OVERRUN;
+            rec.ExceptionAddress = (void *)ctx.Pc;
+            rec.ExceptionFlags = EH_NONCONTINUABLE;
+            rec.NumberParameters = 1;
+            rec.ExceptionInformation[0] = ctx.R0;
+            NtRaiseException( &rec, &ctx, 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;

--- a/dlls/ntdll/unix/signal_arm64.c
+++ b/dlls/ntdll/unix/signal_arm64.c
@@ -908,6 +908,7 @@ 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;

    switch (siginfo->si_code)
    {
@@ -916,6 +917,21 @@ static void trap_handler( int signal, siginfo_t *siginfo, void *sigcontext )
        break;
    case TRAP_BRKPT:
    default:
+        /* debug exceptions do not update ESR on Linux, so we fetch the instruction directly. */
+        if (!(PSTATE_sig( context ) & 0x10) && /* AArch64 (not WoW) */
+            !(PC_sig( context ) & 3) &&
+            *(ULONG *)PC_sig( context ) == 0xd43e0060UL) /* brk #0xf003 -> __fastfail */
+        {
+            CONTEXT ctx;
+            save_context( &ctx, sigcontext );
+            rec.ExceptionCode = STATUS_STACK_BUFFER_OVERRUN;
+            rec.ExceptionAddress = (void *)ctx.Pc;
+            rec.ExceptionFlags = EH_NONCONTINUABLE;
+            rec.NumberParameters = 1;
+            rec.ExceptionInformation[0] = ctx.u.X[0];
+            NtRaiseException( &rec, &ctx, FALSE );
+            return;
+        }
        rec.ExceptionCode = EXCEPTION_BREAKPOINT;
        rec.NumberParameters = 1;
        break;

--- a/dlls/ntdll/unix/signal_i386.c
+++ b/dlls/ntdll/unix/signal_i386.c
@@ -1676,6 +1676,14 @@ static BOOL handle_interrupt( unsigned int interrupt, ucontext_t *sigcontext, vo

    switch(interrupt)
    {
+    case 0x29:
+        /* __fastfail: process state is corrupted */
+        rec->ExceptionCode = STATUS_STACK_BUFFER_OVERRUN;
+        rec->ExceptionFlags = EH_NONCONTINUABLE;
+        rec->NumberParameters = 1;
+        rec->ExceptionInformation[0] = context->Ecx;
+        NtRaiseException( rec, context, FALSE );
+        return TRUE;
    case 0x2d:
        if (!is_wow64)
        {

--- a/dlls/ntdll/unix/signal_x86_64.c
+++ b/dlls/ntdll/unix/signal_x86_64.c
@@ -2486,6 +2486,14 @@ static inline BOOL handle_interrupt( ucontext_t *sigcontext, EXCEPTION_RECORD *r

    switch (ERROR_sig(sigcontext) >> 3)
    {
+    case 0x29:
+        /* __fastfail: process state is corrupted */
+        rec->ExceptionCode = STATUS_STACK_BUFFER_OVERRUN;
+        rec->ExceptionFlags = EH_NONCONTINUABLE;
+        rec->NumberParameters = 1;
+        rec->ExceptionInformation[0] = context->Rcx;
+        NtRaiseException( rec, context, FALSE );
+        return TRUE;
    case 0x2c:
        rec->ExceptionCode = STATUS_ASSERTION_FAILURE;
        break;