Alexandre Julliard : ntdll: Handle invalid %gs fault in signal handler on i386.
Alexandre Julliard
julliard at winehq.org
Thu Sep 12 16:28:56 CDT 2019
Module: wine
Branch: master
Commit: 58139dcb125390b9a2bcd79869d571337d8ab3d8
URL: https://source.winehq.org/git/wine.git/?a=commit;h=58139dcb125390b9a2bcd79869d571337d8ab3d8
Author: Alexandre Julliard <julliard at winehq.org>
Date: Thu Sep 12 20:00:48 2019 +0200
ntdll: Handle invalid %gs fault in signal handler on i386.
Signed-off-by: Alexandre Julliard <julliard at winehq.org>
---
dlls/ntdll/signal_i386.c | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)
diff --git a/dlls/ntdll/signal_i386.c b/dlls/ntdll/signal_i386.c
index 9ce318c27d..9511255754 100644
--- a/dlls/ntdll/signal_i386.c
+++ b/dlls/ntdll/signal_i386.c
@@ -1594,18 +1594,19 @@ static inline DWORD is_privileged_instr( CONTEXT *context )
*
* Check for fault caused by invalid %gs value (some copy protection schemes mess with it).
*/
-static inline BOOL check_invalid_gs( CONTEXT *context )
+static inline BOOL check_invalid_gs( ucontext_t *sigcontext, CONTEXT *context )
{
- unsigned int prefix_count = 0;
- const BYTE *instr = (BYTE *)context->Eip;
+ BYTE instr[14];
+ unsigned int i, len;
WORD system_gs = x86_thread_data()->gs;
if (context->SegGs == system_gs) return FALSE;
if (!wine_ldt_is_system( context->SegCs )) return FALSE;
/* only handle faults in system libraries */
- if (virtual_is_valid_code_address( instr, 1 )) return FALSE;
+ if (virtual_is_valid_code_address( (BYTE *)context->Eip, 1 )) return FALSE;
- for (;;) switch(*instr)
+ len = virtual_uninterrupted_read_memory( (BYTE *)context->Eip, instr, sizeof(instr) );
+ for (i = 0; i < len; i++) switch (instr[i])
{
/* instruction prefixes */
case 0x2e: /* %cs: */
@@ -1618,16 +1619,17 @@ static inline BOOL check_invalid_gs( CONTEXT *context )
case 0xf0: /* lock */
case 0xf2: /* repne */
case 0xf3: /* repe */
- if (++prefix_count >= 15) return FALSE;
- instr++;
continue;
case 0x65: /* %gs: */
TRACE( "%04x/%04x at %p, fixing up\n", context->SegGs, system_gs, instr );
- context->SegGs = system_gs;
+#ifdef GS_sig
+ GS_sig(sigcontext) = system_gs;
+#endif
return TRUE;
default:
return FALSE;
}
+ return FALSE;
}
@@ -1911,8 +1913,6 @@ static void WINAPI raise_segv_exception( EXCEPTION_RECORD *rec, CONTEXT *context
case EXCEPTION_ACCESS_VIOLATION:
if (rec->NumberParameters == 2)
{
- if (rec->ExceptionInformation[1] == 0xffffffff && check_invalid_gs( context ))
- goto done;
if (!(rec->ExceptionCode = virtual_handle_fault( (void *)rec->ExceptionInformation[1],
rec->ExceptionInformation[0], FALSE )))
goto done;
@@ -2059,7 +2059,10 @@ static void segv_handler( int signal, siginfo_t *siginfo, void *sigcontext )
if ((err & 7) == 4 && !wine_ldt_is_system( err | 7 ))
stack->rec.ExceptionInformation[1] = err & ~7;
else
+ {
stack->rec.ExceptionInformation[1] = 0xffffffff;
+ if (check_invalid_gs( context, &stack->context )) return;
+ }
}
break;
case TRAP_x86_PAGEFLT: /* Page fault */
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