Date: Wed, 14 Dec 2016 12:56:14 +0800 From: Herbert Xu <herbert@...dor.apana.org.au> To: Andy Lutomirski <luto@...capital.net> Cc: Eric Biggers <ebiggers3@...il.com>, linux-crypto@...r.kernel.org, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "linux-mm@...ck.org" <linux-mm@...ck.org>, "kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>, Andrew Lutomirski <luto@...nel.org>, Stephan Mueller <smueller@...onox.de> Subject: Re: Remaining crypto API regressions with CONFIG_VMAP_STACK On Tue, Dec 13, 2016 at 09:06:31AM -0800, Andy Lutomirski wrote: > > > Having 0 as type and CRYPTO_ALG_ASYNC as mask in general means > > that we're requesting a sync algorithm (i.e., ASYNC bit off). > > > > However, it is completely unnecessary for shash as they can never > > be async. So this could be changed to just ("michael_mic", 0, 0). > > I'm confused by a bunch of this. > > 1. Is it really the case that crypto_alloc_xyz(..., CRYPTO_ALG_ASYNC) > means to allocate a *synchronous* transform? That's not what I > expected. crypto_alloc_xyz(name, 0, CRYPTO_ALG_ASYNC) allocates a sync tfm and crypto_alloc_xyz(name, CRYPTO_ALG_ASYNC, CRYPTO_ALG_ASYNC) allocates an async tfm while crypto_alloc_xyz(name, 0, 0) does not care whether the allocated tfm is sync or asnc. > 2. What guarantees that an async request is never allocated on the > stack? If it's just convention, could an assertion be added > somewhere? Sure we can add an assertion. Cheers, -- Email: Herbert Xu <herbert@...dor.apana.org.au> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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