Re: SSE related security hole

linux
2002-04-18T18:36:49Z

Um, people here seem to be assuming that, in the absence of MMX,
fninit *doesn't* leak information.

I thought it was well-known to just clear (set to all-ones) the
tag register and not alter the actual floating-point registers.

Thus, it seems quite feasible to reset the tag word with FLDENV and
store out the FPU registers, even on an 80387.

Isn't this the same security hole? Shouldn't there be 8 FLDZ instructions
(or equivalent) in the processor state initialization?