linux-kernel - Re: [PATCH] crypto: x86/chacha - avoid sleeping under kernel_fpu

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Date:   Sun, 23 Dec 2018 12:03:13 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Eric Biggers <ebiggers@...nel.org>
Cc:     linux-crypto@...r.kernel.org, syzkaller-bugs@...glegroups.com,
        davem@...emloft.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] crypto: x86/chacha - avoid sleeping under
 kernel_fpu_begin()

On Sat, Dec 15, 2018 at 12:40:17PM -0800, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@...gle.com>
> 
> Passing atomic=true to skcipher_walk_virt() only makes the later
> skcipher_walk_done() calls use atomic memory allocations, not
> skcipher_walk_virt() itself.  Thus, we have to move it outside of the
> preemption-disabled region (kernel_fpu_begin()/kernel_fpu_end()).
> 
> (skcipher_walk_virt() only allocates memory for certain layouts of the
> input scatterlist, hence why I didn't notice this earlier...)
> 
> Reported-by: syzbot+9bf843c33f782d73ae7d@...kaller.appspotmail.com
> Fixes: 4af78261870a ("crypto: x86/chacha20 - add XChaCha20 support")
> Signed-off-by: Eric Biggers <ebiggers@...gle.com>
> ---
>  arch/x86/crypto/chacha_glue.c | 33 ++++++++++++++++++++-------------
>  1 file changed, 20 insertions(+), 13 deletions(-)

Patch applied.  Thanks.
-- 
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