linux-kernel - Re: [PATCH] crypto: Pad aes_ccm_enc_tv

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Date:   Wed, 1 Mar 2017 19:52:20 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Laura Abbott <labbott@...hat.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>
Subject: Re: [PATCH] crypto: Pad aes_ccm_enc_tv_template vector

On Tue, Feb 28, 2017 at 02:07:25PM -0800, Laura Abbott wrote:
> Running with KASAN and crypto tests currently gives
> 
>  BUG: KASAN: global-out-of-bounds in __test_aead+0x9d9/0x2200 at addr ffffffff8212fca0
>  Read of size 16 by task cryptomgr_test/1107
>  Address belongs to variable 0xffffffff8212fca0
>  CPU: 0 PID: 1107 Comm: cryptomgr_test Not tainted 4.10.0+ #45
>  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.1-1.fc24 04/01/2014
>  Call Trace:
>   dump_stack+0x63/0x8a
>   kasan_report.part.1+0x4a7/0x4e0
>   ? __test_aead+0x9d9/0x2200
>   ? crypto_ccm_init_crypt+0x218/0x3c0 [ccm]
>   kasan_report+0x20/0x30
>   check_memory_region+0x13c/0x1a0
>   memcpy+0x23/0x50
>   __test_aead+0x9d9/0x2200
>   ? kasan_unpoison_shadow+0x35/0x50
>   ? alg_test_akcipher+0xf0/0xf0
>   ? crypto_skcipher_init_tfm+0x2e3/0x310
>   ? crypto_spawn_tfm2+0x37/0x60
>   ? crypto_ccm_init_tfm+0xa9/0xd0 [ccm]
>   ? crypto_aead_init_tfm+0x7b/0x90
>   ? crypto_alloc_tfm+0xc4/0x190
>   test_aead+0x28/0xc0
>   alg_test_aead+0x54/0xd0
>   alg_test+0x1eb/0x3d0
>   ? alg_find_test+0x90/0x90
>   ? __sched_text_start+0x8/0x8
>   ? __wake_up_common+0x70/0xb0
>   cryptomgr_test+0x4d/0x60
>   kthread+0x173/0x1c0
>   ? crypto_acomp_scomp_free_ctx+0x60/0x60
>   ? kthread_create_on_node+0xa0/0xa0
>   ret_from_fork+0x2c/0x40
>  Memory state around the buggy address:
>   ffffffff8212fb80: 00 00 00 00 01 fa fa fa fa fa fa fa 00 00 00 00
>   ffffffff8212fc00: 00 01 fa fa fa fa fa fa 00 00 00 00 01 fa fa fa
>  >ffffffff8212fc80: fa fa fa fa 00 05 fa fa fa fa fa fa 00 00 00 00
>                                    ^
>   ffffffff8212fd00: 01 fa fa fa fa fa fa fa 00 00 00 00 01 fa fa fa
>   ffffffff8212fd80: fa fa fa fa 00 00 00 00 00 05 fa fa fa fa fa fa
> 
> This always happens on the same IV which is less than 16 bytes.
> 
> Per Ard,
> 
> "CCM IVs are 16 bytes, but due to the way they are constructed
> internally, the final couple of bytes of input IV are dont-cares.
> 
> Apparently, we do read all 16 bytes, which triggers the KASAN errors."
> 
> Fix this by padding the IV with null bytes to be at least 16 bytes.
> 
> Fixes: 0bc5a6c5c79a ("crypto: testmgr - Disable rfc4309 test and convert
> test vectors")
> Acked-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> Signed-off-by: Laura Abbott <labbott@...hat.com>

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