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    Subject[PATCH 4.14 085/167] selftests/x86/mpx: Fix incorrect bounds with old _sigfault
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Rui Wang <rui.y.wang@intel.com>

    commit 961888b1d76d84efc66a8f5604b06ac12ac2f978 upstream.

    For distributions with old userspace header files, the _sigfault
    structure is different. mpx-mini-test fails with the following
    error:

    [root@Purley]# mpx-mini-test_64 tabletest
    XSAVE is supported by HW & OS
    XSAVE processor supported state mask: 0x2ff
    XSAVE OS supported state mask: 0x2ff
    BNDREGS: size: 64 user: 1 supervisor: 0 aligned: 0
    BNDCSR: size: 64 user: 1 supervisor: 0 aligned: 0
    starting mpx bounds table test
    ERROR: siginfo bounds do not match shadow bounds for register 0

    Fix it by using the correct offset of _lower/_upper in _sigfault.
    RHEL needs this patch to work.

    Signed-off-by: Rui Wang <rui.y.wang@intel.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: dave.hansen@linux.intel.com
    Fixes: e754aedc26ef ("x86/mpx, selftests: Add MPX self test")
    Link: http://lkml.kernel.org/r/1513586050-1641-1-git-send-email-rui.y.wang@intel.com
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    tools/testing/selftests/x86/mpx-mini-test.c | 32 ++++++++++++++++++++++++++--
    1 file changed, 30 insertions(+), 2 deletions(-)

    --- a/tools/testing/selftests/x86/mpx-mini-test.c
    +++ b/tools/testing/selftests/x86/mpx-mini-test.c
    @@ -315,11 +315,39 @@ static inline void *__si_bounds_upper(si
    return si->si_upper;
    }
    #else
    +
    +/*
    + * This deals with old version of _sigfault in some distros:
    + *
    +
    +old _sigfault:
    + struct {
    + void *si_addr;
    + } _sigfault;
    +
    +new _sigfault:
    + struct {
    + void __user *_addr;
    + int _trapno;
    + short _addr_lsb;
    + union {
    + struct {
    + void __user *_lower;
    + void __user *_upper;
    + } _addr_bnd;
    + __u32 _pkey;
    + };
    + } _sigfault;
    + *
    + */
    +
    static inline void **__si_bounds_hack(siginfo_t *si)
    {
    void *sigfault = &si->_sifields._sigfault;
    void *end_sigfault = sigfault + sizeof(si->_sifields._sigfault);
    - void **__si_lower = end_sigfault;
    + int *trapno = (int*)end_sigfault;
    + /* skip _trapno and _addr_lsb */
    + void **__si_lower = (void**)(trapno + 2);

    return __si_lower;
    }
    @@ -331,7 +359,7 @@ static inline void *__si_bounds_lower(si

    static inline void *__si_bounds_upper(siginfo_t *si)
    {
    - return (*__si_bounds_hack(si)) + sizeof(void *);
    + return *(__si_bounds_hack(si) + 1);
    }
    #endif


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