linux-kernel - Re: [PATCH next] crypto: fix oob Read in arc4

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Date: Thu, 21 Dec 2023 09:32:40 +0800
From: Herbert Xu <herbert@...dor.apana.org.au>
To: Edward Adam Davis <eadavis@...com>
Cc: syzbot+8ffb0839a24e9c6bfa76@...kaller.appspotmail.com,
	davem@...emloft.net, linux-crypto@...r.kernel.org,
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH next] crypto: fix oob Read in arc4_crypt

On Wed, Dec 20, 2023 at 11:53:55PM +0800, Edward Adam Davis wrote:
> The space allocated to areq is not sufficient to access the member __ctx of 
> struct skcipher_request, as the space occupied by struct arc4_ctx for reading 
> is 1032 bytes, while the requested memory size in skcipher_recvmsg() is:
> sizeof(struct af_alg_async_req) + crypto_skcipher_reqsize(tfm) = 736 bytes,
> which does not include the memory required for __ctx of struct skcipher_request.
> 
> Reported-by: syzbot+8ffb0839a24e9c6bfa76@...kaller.appspotmail.com
> Signed-off-by: Edward Adam Davis <eadavis@...com>
> ---
>  crypto/algif_skcipher.c            | 10 +++++++---
>  crypto/skcipher.c                  |  1 -
>  include/crypto/internal/skcipher.h |  1 +
>  3 files changed, 8 insertions(+), 4 deletions(-)

I see where the real bug is.  The statesize is not being passed
along by ecb so that's why we end up with no memory.

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