Re: ia32 binfmt problem with x86-64

[Arjan van de Ven <arjan@infradead.org>]

On Mon, 2006-06-26 at 01:43 +0200, Markus Schoder wrote:
> The 32 bit emulation for x86-64 has the following in 
> arch/x86_64/ia32/ia32_binfmt.c:
> 
> #define elf_read_implies_exec(ex, have_pt_gnu_stack)	  \
>   (!(have_pt_gnu_stack))
> 
> I guess it should be same definition as in include/asm-i386/elf.h and 
> include/asm-x86_64/elf.h instead:
> 
> #define elf_read_implies_exec(ex, executable_stack) \
>   (executable_stack != EXSTACK_DISABLE_X)
> 
> >From the usage in fs/binfmt_elf.c it looks like the semantics of that 
> macro changed slightly but was not fixed in all places (ia64 seems to 
> have a similar problem from the looks of it).
> 
> The current behavior leads to 32 bit executables not setting the 
> READ_IMPLIES_EXEC personality when they are marked as requiring an 
> executable stack (64 bit executables do however).

Hi,

regardless of the inconsistency you found; I think the behavior is
correct. "Legacy" binaries get read-implies-exec (since that is the old
behavior), "new" binaries get "we honor the stack you set". Why should
read-implies-exec be set when an application asks for an executable
stack? I disagree that it should be set; the application should just use
the proper PROT_EXEC flags for its allocations; now it's not an option
to fix legacy apps (the ones without the pt_gnu_stack marker), but for
new things for sure is/was; this has been the case for the last... 3+
years already.

So... fix the app ! (and.. which app is this ?)

Greetings,
    Arjan van de Ven

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