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Dave Hansen authored
MPX decodes instructions in order to tell which bounds register was violated. Part of this decoding involves looking at the "REX prefix" which is a special instrucion prefix used to retrofit support for new registers in to old instructions. The X86_REX_*() macros are defined to return actual bit values: #define X86_REX_R(rex) ((rex) & 4) *not* boolean values. However, the MPX code was checking for them like they were booleans. This might have led to us mis-decoding the "REX prefix" and giving false information out to userspace about bounds violations. X86_REX_B() actually is bit 1, so this is really only broken for the X86_REX_X() case. Fix the conditionals up to tolerate the non-boolean values. Fixes: fcc7ffd6 "x86, mpx: Decode MPX instruction to get bound violation information" Reported-by:
Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by:
Dave Hansen <dave.hansen@linux.intel.com> Cc: x86@kernel.org Cc: Dave Hansen <dave@sr71.net> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20151201003113.D800C1E0@viggo.jf.intel.comSigned-off-by:
Thomas Gleixner <tglx@linutronix.de>
8e8efe03