Re: Crypto Fixes for 4.12

From	David Miller <davem@davemloft.net>
Newsgroups	linux.kernel
Subject	Re: Crypto Fixes for 4.12
Date	2017-06-16 19:00 +0200
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From: Theodore Ts'o <tytso@mit.edu>
Date: Fri, 16 Jun 2017 08:50:07 -0400

> On Thu, Jun 15, 2017 at 11:01:18AM -0400, David Miller wrote:
>> As a side note, ext4 does something similar with a private
>> implementation, but it doesn't use something the evaluates to an
>> alloca.  Instead it uses a fixed 4-byte size for the shash context
>> value in the on-stack declaration.
> 
> In ext4's case, we're doing it inside an inline function, and then
> using the "return" value from inside the calling function.  Assuming
> that gcc actually inlines the function, are we in danger of tripping
> over the bug?

Again, the bug can only be triggered if you do a dynamically sized
object on the stack.

Which ext4 is not doing, since it uses fixed size elements in the
on-stack shash context.

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Thread

Crypto Fixes for 4.12 Herbert Xu <herbert@gondor.apana.org.au> - 2017-06-08 11:30 +0200
  Re: Crypto Fixes for 4.12 David Miller <davem@davemloft.net> - 2017-06-08 16:10 +0200
    Re: Crypto Fixes for 4.12 Herbert Xu <herbert@gondor.apana.org.au> - 2017-06-09 05:00 +0200
  Crypto Fixes for 4.12 Herbert Xu <herbert@gondor.apana.org.au> - 2017-06-15 03:00 +0200
    Re: Crypto Fixes for 4.12 Linus Torvalds <torvalds@linux-foundation.org> - 2017-06-15 11:10 +0200
      Re: Crypto Fixes for 4.12 Linus Torvalds <torvalds@linux-foundation.org> - 2017-06-15 11:10 +0200
      Re: Crypto Fixes for 4.12 Herbert Xu <herbert@gondor.apana.org.au> - 2017-06-15 11:50 +0200
        Re: Crypto Fixes for 4.12 David Miller <davem@davemloft.net> - 2017-06-15 17:10 +0200
      Re: Crypto Fixes for 4.12 David Miller <davem@davemloft.net> - 2017-06-15 17:10 +0200
        Re: Crypto Fixes for 4.12 Theodore Ts'o <tytso@mit.edu> - 2017-06-16 15:00 +0200
          Re: Crypto Fixes for 4.12 David Miller <davem@davemloft.net> - 2017-06-16 19:00 +0200

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