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From: Paul Brook <paul@codesourcery.com>
Date: Sat, 13 Mar 2010 00:45:22 +0000
References: <alpine.LNX.2.00.1003130314190.6704@linmac>
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Subject: [Qemu-devel] Re: linux-user issues
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To: malc <av1474@comtv.ru>
Cc: qemu-devel@nongnu.org, Aurelien Jarno <aurelien@aurel32.net>

> a) elfload.c:859
> 
>    #define TARGET_ELF_PAGESTART(_v) ((_v) & ~(unsigned
>  long)(TARGET_ELF_EXEC_PAGESIZE-1))
> 
>    This means that for 64bit guest on a 32bit host the _v's value is
>    silently reduced to 32bit, the cast should be abi_ulong.
> 
> b) mmap.c:428
> 
>    real_start = start & qemu_host_page_mask;
> 
>    Same thing basically qemu_host_page_mask is unsigned long and so
>    the upper bits are sliently cleared. Again qemu_host_page_mask
>    should probably be abi_ulong.
> 
> The above two make elf binary with one of the segments above 4G load
> and run on 32bit guest only to fail well into execution and without
> any indication that it shouldn't have been allowed to run in the first
> place.

I'd be amazed if these are the only two issues, and expect 64-bit guests on 
32-bit hosts to be generally unsafe.

Paul