[PATCH] ntdll: Ensure CONTEXT_EX on exception stack is initialized.
Brendan Shanks
bshanks at codeweavers.com
Thu Mar 3 12:24:22 CST 2022
On non-AVX CPUs, CONTEXT_EX is not being initialized.
In WOW64 mode, this results in invalid exception records when
dispatch_wow_exception() uses RtlCopyContext().
Signed-off-by: Brendan Shanks <bshanks at codeweavers.com>
---
- The XState/All lengths come from RtlInitializeExtendedContext2().
- I only experienced the bug on x86_64, but made the i386 change for
consistency.
dlls/ntdll/unix/signal_i386.c | 23 +++++++++++++++++++----
dlls/ntdll/unix/signal_x86_64.c | 23 +++++++++++++++++++----
2 files changed, 38 insertions(+), 8 deletions(-)
diff --git a/dlls/ntdll/unix/signal_i386.c b/dlls/ntdll/unix/signal_i386.c
index 6bb5649e2b5..e2a6148d609 100644
--- a/dlls/ntdll/unix/signal_i386.c
+++ b/dlls/ntdll/unix/signal_i386.c
@@ -581,12 +581,23 @@ static inline void context_init_xstate( CONTEXT *context, void *xstate_buffer )
xctx->Legacy.Length = sizeof(CONTEXT);
xctx->Legacy.Offset = -(LONG)sizeof(CONTEXT);
- xctx->XState.Length = sizeof(XSTATE);
- xctx->XState.Offset = (BYTE *)xstate_buffer - (BYTE *)xctx;
+ if (xstate_buffer)
+ {
+ xctx->XState.Length = sizeof(XSTATE);
+ xctx->XState.Offset = (BYTE *)xstate_buffer - (BYTE *)xctx;
+ context->ContextFlags |= CONTEXT_XSTATE;
+
+ xctx->All.Length = sizeof(CONTEXT) + xctx->XState.Offset + xctx->XState.Length;
+ }
+ else
+ {
+ xctx->XState.Length = 25;
+ xctx->XState.Offset = 0;
+
+ xctx->All.Length = sizeof(CONTEXT) + 24; /* sizeof(CONTEXT_EX) minus 8 alignment bytes on x64. */
+ }
- xctx->All.Length = sizeof(CONTEXT) + xctx->XState.Offset + xctx->XState.Length;
xctx->All.Offset = -(LONG)sizeof(CONTEXT);
- context->ContextFlags |= CONTEXT_XSTATE;
}
@@ -1456,6 +1467,10 @@ C_ASSERT( (offsetof(struct stack_layout, xstate) == sizeof(struct stack_layout))
memcpy( &dst_xs->YmmContext, &src_xs->YmmContext, sizeof(dst_xs->YmmContext) );
}
}
+ else
+ {
+ context_init_xstate( &stack->context, NULL );
+ }
stack->rec_ptr = &stack->rec;
stack->context_ptr = &stack->context;
diff --git a/dlls/ntdll/unix/signal_x86_64.c b/dlls/ntdll/unix/signal_x86_64.c
index ac67e12240a..29096261723 100644
--- a/dlls/ntdll/unix/signal_x86_64.c
+++ b/dlls/ntdll/unix/signal_x86_64.c
@@ -413,12 +413,23 @@ static inline void context_init_xstate( CONTEXT *context, void *xstate_buffer )
xctx->Legacy.Length = sizeof(CONTEXT);
xctx->Legacy.Offset = -(LONG)sizeof(CONTEXT);
- xctx->XState.Length = sizeof(XSTATE);
- xctx->XState.Offset = (BYTE *)xstate_buffer - (BYTE *)xctx;
+ if (xstate_buffer)
+ {
+ xctx->XState.Length = sizeof(XSTATE);
+ xctx->XState.Offset = (BYTE *)xstate_buffer - (BYTE *)xctx;
+ context->ContextFlags |= CONTEXT_XSTATE;
+
+ xctx->All.Length = sizeof(CONTEXT) + xctx->XState.Offset + xctx->XState.Length;
+ }
+ else
+ {
+ xctx->XState.Length = 25;
+ xctx->XState.Offset = 0;
+
+ xctx->All.Length = sizeof(CONTEXT) + 24; /* sizeof(CONTEXT_EX) minus 8 alignment bytes on x64. */
+ }
- xctx->All.Length = sizeof(CONTEXT) + xctx->XState.Offset + xctx->XState.Length;
xctx->All.Offset = -(LONG)sizeof(CONTEXT);
- context->ContextFlags |= CONTEXT_XSTATE;
}
static USHORT cs32_sel; /* selector for %cs in 32-bit mode */
@@ -2198,6 +2209,10 @@ static void setup_raise_exception( ucontext_t *sigcontext, EXCEPTION_RECORD *rec
memcpy( &dst_xs->YmmContext, &src_xs->YmmContext, sizeof(dst_xs->YmmContext) );
}
}
+ else
+ {
+ context_init_xstate( &stack->context, NULL );
+ }
CS_sig(sigcontext) = cs64_sel;
RIP_sig(sigcontext) = (ULONG_PTR)pKiUserExceptionDispatcher;
--
2.32.0 (Apple Git-132)
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