[tor-bugs] #13912 [Tor]: Key Security: Zeroing Buffers Is Insufficient (AES-NI leaves keys in SSE registers)

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#13912: Key Security: Zeroing Buffers Is Insufficient (AES-NI leaves keys in SSE
registers)
------------------------+--------------------------------
     Reporter:  teor    |      Owner:
         Type:  defect  |     Status:  new
     Priority:  normal  |  Milestone:  Tor: 0.2.???
    Component:  Tor     |    Version:  Tor: 0.2.6.1-alpha
   Resolution:          |   Keywords:  security
Actual Points:          |  Parent ID:
       Points:          |
------------------------+--------------------------------

Comment (by nickm):

 Well, there's no *portable*, *standards-guaranteed* way to sanitize the
 stack.  But in practice you can probably call a function that does
 something like.

 {{{
   void stomp_stack(void) __attribute__((noinline));
   void stomp_stack(void)
   {
       unsigned char huge[256*1024];
       memset_s(huge, sizeof(huge), 0, sizeof(huge));
   }
 }}}

 But of course, you wouldn't want to do that too often.

 WRT the original question of SSE registers, Yawning had some interesting
 points on IRC today. I hope he can summarize.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/13912#comment:4>
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