Attachment 36 Details for Bug 154 – Вариант патча

Вариант патча

variants_to_solve (text/plain), 2.67 KB, created by Константин Петров on 2010-11-18 03:58:26 MSK

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Creator: Константин Петров

Created: 2010-11-18 03:58:26 MSK

Size: 2.67 KB

patch

obsolete

>Hi,
>
>Below are the outputs from a sample program that does a call to an invalid address. The first trace is without the patch and the second is with.
>
>=>1 0x7fe3704c INSTR_EmulateInstruction+0xb8(rec=0x7fbbfe2c, context=0x7fbbfb60) [/home/rob/wine/dlls/kernel/instr.c:455] in kernel32 (0x7fbbfa90)
> 2 0x7fe700f3 vectored_handler(ptrs=0x7fbbfacc) [/home/rob/wine/dlls/kernel/wowthunk.c:357] in kernel32 (0x7fbbfaac)
>  3 0xb7e39082 __regs_RtlRaiseException+0xc2(rec=0x7fbbfe2c, context=0x7fbbfb60) [/home/rob/wine/dlls/ntdll/exception.c:196] in ntdll (0x7fbbfb30)
>   4 0xb7e54b7f raise_segv_exception(rec=0x7fbbfe2c, context=0x7fbbfb60) [/home/rob/wine/dlls/ntdll/signal_i386.c:887] in ntdll (0x7fbbfb4c)
>    5 0xb7e5d4d4 __wine_call_from_32_restore_regs in ntdll (0x7fbbfe9c)
>     6 0x7fbde163 __wine_exe_main in winver (0x7fbbff2c)
>      7 0x7fe504ff start_process(arg=0x0) [/home/rob/wine/dlls/kernel/process.c:1044] in kernel32 (0x7fbbfff4)
>       8 0xb7fc0535 wine_switch_to_stack+0x11 in libwine.so.1 (0x00000000)
>       0x7fe3704c INSTR_EmulateInstruction+0xb8 [/home/rob/wine/dlls/kernel/instr.c:455] in kernel32: movb     0x0(%edi),%dl
>       455             switch(*instr)
>       
>       Backtrace:
>       =>1 0x0000cccc (0x7fbbfe9c)
>        2 0x7fbde163 __wine_exe_main+0x163 in winver (0x7fbbff2c)
>	 3 0x7fe504ff start_process+0xc3(arg=0x0) [/home/rob/wine/dlls/kernel/process.c:1044] in kernel32 (0x7fbbfff4)
>	  4 0xb7fc0535 wine_switch_to_stack+0x11 in libwine.so.1 (0x00000000)
>	  0x0000cccc: addb        %al,0x0(%eax)
>	  
>	  Therefore this patch aids in debugging. It isn't perfect because of x86's variable length instructions, but it is fairly unlikely that an instruction will straddle a page boundary and the first page be readable and the second not.
>	  
>	  Changelog:
>	  Make instruction emulation code more tolerant of bad addresses by checking the instruction pointer refers to readable memory.
>	  
>	  -- 
>	  Rob Shearman
>	  
>	  
>	  
>	  Index: dlls/kernel/instr.c
>	  ===================================================================
>	  RCS file: /home/wine/wine/dlls/kernel/instr.c,v
>	  retrieving revision 1.22
>	  diff -u -p -r1.22 instr.c
>	  --- dlls/kernel/instr.c	31 May 2005 13:28:42 -0000	1.22
>	  +++ dlls/kernel/instr.c	19 Jun 2005 03:41:17 -0000
>	  @@ -443,6 +443,7 @@ DWORD INSTR_EmulateInstruction( EXCEPTIO
>	       long_op = long_addr = (!ISV86(context) && IS_SELECTOR_32BIT(context->SegCs));
>	            instr = make_ptr( context, context->SegCs, context->Eip, TRUE );
>		         if (!instr) return ExceptionContinueSearch;
>			 +    if (IsBadReadPtr(instr, 1)) return ExceptionContinueSearch;
>			  
>			      /* First handle any possible prefix */
>			       
>			      
>			      
>			      
>

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