linux-kernel - Re: [PATCH v2 13/15] crypto: testmgr - convert hash testing to use testvec

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Date:   Thu, 29 Aug 2019 17:32:46 +0200
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Eric Biggers <ebiggers@...nel.org>, linux-crypto@...r.kernel.org,
        Herbert Xu <herbert@...dor.apana.org.au>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 13/15] crypto: testmgr - convert hash testing to use
 testvec_configs

Hi Eric,


Le 01/02/2019 à 08:51, Eric Biggers a écrit :
> From: Eric Biggers <ebiggers@...gle.com>
> 
> Convert alg_test_hash() to use the new test framework, adding a list of
> testvec_configs to test by default.  When the extra self-tests are
> enabled, randomly generated testvec_configs are tested as well.
> 
> This improves hash test coverage mainly because now all algorithms have
> a variety of data layouts tested, whereas before each algorithm was
> responsible for declaring its own chunked test cases which were often
> missing or provided poor test coverage.  The new code also tests both
> the MAY_SLEEP and !MAY_SLEEP cases and buffers that cross pages.
> 
> This already found bugs in the hash walk code and in the arm32 and arm64
> implementations of crct10dif.
> 
> I removed the hash chunked test vectors that were the same as
> non-chunked ones, but left the ones that were unique.
> 
> Signed-off-by: Eric Biggers <ebiggers@...gle.com>
> ---
>   crypto/testmgr.c | 795 ++++++++++++++++++++---------------------------
>   crypto/testmgr.h | 107 +------
>   2 files changed, 352 insertions(+), 550 deletions(-)
> 
> diff --git a/crypto/testmgr.c b/crypto/testmgr.c
> index 7638090ff1b0a..96aa268ff4184 100644
> --- a/crypto/testmgr.c
> +++ b/crypto/testmgr.c

[...]


> -static int __test_hash(struct crypto_ahash *tfm,
> -		       const struct hash_testvec *template, unsigned int tcount,
> -		       enum hash_test test_type, const int align_offset)
> +static int test_hash_vec_cfg(const char *driver,
> +			     const struct hash_testvec *vec,
> +			     unsigned int vec_num,
> +			     const struct testvec_config *cfg,
> +			     struct ahash_request *req,
> +			     struct test_sglist *tsgl,
> +			     u8 *hashstate)
>   {
> -	const char *algo = crypto_tfm_alg_driver_name(crypto_ahash_tfm(tfm));
> -	size_t digest_size = crypto_ahash_digestsize(tfm);
> -	unsigned int i, j, k, temp;
> -	struct scatterlist sg[8];
> -	char *result;
> -	char *key;
> -	struct ahash_request *req;
> -	struct crypto_wait wait;
> -	void *hash_buff;
> -	char *xbuf[XBUFSIZE];
> -	int ret = -ENOMEM;
> -
> -	result = kmalloc(digest_size, GFP_KERNEL);
> -	if (!result)
> -		return ret;
> -	key = kmalloc(MAX_KEYLEN, GFP_KERNEL);
> -	if (!key)
> -		goto out_nobuf;
> -	if (testmgr_alloc_buf(xbuf))
> -		goto out_nobuf;
> +	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
> +	const unsigned int alignmask = crypto_ahash_alignmask(tfm);
> +	const unsigned int digestsize = crypto_ahash_digestsize(tfm);
> +	const unsigned int statesize = crypto_ahash_statesize(tfm);
> +	const u32 req_flags = CRYPTO_TFM_REQ_MAY_BACKLOG | cfg->req_flags;
> +	const struct test_sg_division *divs[XBUFSIZE];
> +	DECLARE_CRYPTO_WAIT(wait);
> +	struct kvec _input;
> +	struct iov_iter input;
> +	unsigned int i;
> +	struct scatterlist *pending_sgl;
> +	unsigned int pending_len;
> +	u8 result[HASH_MAX_DIGESTSIZE + TESTMGR_POISON_LEN];

Before this patch, result was allocated with kmalloc().
Now, result is in the stack. Is there a reason for this change ?

Due to this change, the talitos driver fails when using 
CONFIG_VMAP_STACK, because result is not dma-able anymore.

CONFIG_DEBUG_VIRTUAL warns on:

[    4.276401] WARNING: CPU: 0 PID: 72 at 
./arch/powerpc/include/asm/io.h:804 dma_direct_map_page+0x50/0x178
[    4.285725] CPU: 0 PID: 72 Comm: cryptomgr_test Tainted: G        W 
       5.3.0-rc6-s3k-dev-00897-g03e8e9014403-dirty #2182
	[snip registers]
[    4.353542] NIP [c0066eac] dma_direct_map_page+0x50/0x178
[    4.358872] LR [c0066eac] dma_direct_map_page+0x50/0x178
[    4.364074] Call Trace:
[    4.366533] [c9d0fc18] [c0066eac] dma_direct_map_page+0x50/0x178 
(unreliable)
[    4.373587] [c9d0fc38] [c033ac38] __map_single_talitos_ptr+0x54/0x9c
[    4.379869] [c9d0fc48] [c033e878] ahash_process_req+0x318/0x7a8
[    4.385739] [c9d0fca8] [c0210b68] do_ahash_op.isra.0+0x24/0x70
[    4.391494] [c9d0fcb8] [c02130e8] test_ahash_vec_cfg+0x478/0x5a8
[    4.397432] [c9d0fda8] [c0213b40] __alg_test_hash.isra.13+0x16c/0x334
[    4.403797] [c9d0fe08] [c0213d84] alg_test_hash+0x7c/0x164
[    4.409218] [c9d0fe28] [c0213f88] alg_test+0xc0/0x384
[    4.414209] [c9d0fef8] [c020f0ec] cryptomgr_test+0x48/0x50
[    4.419623] [c9d0ff08] [c003a818] kthread+0xe0/0x10c
[    4.424539] [c9d0ff38] [c000e1d0] ret_from_kernel_thread+0x14/0x1c

How should this be fixed ?

Christophe