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    SubjectRe: [PATCHv2] x86/mm: set x32 syscall bit in SET_PERSONALITY()
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    On 03/21/2017 09:40 PM, Cyrill Gorcunov wrote:
    > On Tue, Mar 21, 2017 at 09:09:40PM +0300, Dmitry Safonov wrote:
    >>
    >> I guess the question comes from that we're releasing CRIU 3.0 with
    >> 32-bit C/R and some other cool stuff, but we don't support x32 yet.
    >> As we don't want release a thing that we aren't properly testing.
    >> So for a while we should error on dumping x32 applications.
    >
    > yes
    >
    >> I think, the best way for now is to check physicall address of vdso
    >> from /proc/.../pagemap. If it's CONFIG_VDSO=n kernel, I guess we could
    >> also add check for %ds from ptrace's register set. For x32 it's set to
    >> __USER_DS, while for native it's 0 (looking at start_thread() and
    >> compat_start_thread()). The application can simply change it without
    >> any consequence - so it's not very reliable, we could only warn at
    >> catching it, not rely on this.
    >
    > indeed, thanks!

    Also, even more simple-minded: for now we could just check binary magic
    from /proc/.../exe, for now stopping on x32 binaries.

    --
    Dmitry

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