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Date:   Mon, 25 May 2020 11:45:23 +0800
From:   "Longpeng (Mike, Cloud Infrastructure Service Product Dept.)" 
        <longpeng2@...wei.com>
To:     Jason Wang <jasowang@...hat.com>, <linux-crypto@...r.kernel.org>
CC:     Gonglei <arei.gonglei@...wei.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        <virtualization@...ts.linux-foundation.org>,
        <linux-kernel@...r.kernel.org>,
        LABBE Corentin <clabbe@...libre.com>
Subject: Re: [PATCH 1/2] crypto: virtio: fix src/dst scatterlist calculation

Hi Jason,

On 2020/5/25 11:12, Jason Wang wrote:
> 
> On 2020/5/25 上午8:56, Longpeng(Mike) wrote:
>> The system will crash when we insmod crypto/tcrypt.ko whit mode=38.
>>
>> Usually the next entry of one sg will be @sg@ + 1, but if this sg element
>> is part of a chained scatterlist, it could jump to the start of a new
>> scatterlist array. Let's fix it by sg_next() on calculation of src/dst
>> scatterlist.
>>
>> BTW I add a check for sg_nents_for_len() its return value since
>> sg_nents_for_len() function could fail.
>>
>> Cc: Gonglei <arei.gonglei@...wei.com>
>> Cc: Herbert Xu <herbert@...dor.apana.org.au>
>> Cc: "Michael S. Tsirkin" <mst@...hat.com>
>> Cc: Jason Wang <jasowang@...hat.com>
>> Cc: "David S. Miller" <davem@...emloft.net>
>> Cc: virtualization@...ts.linux-foundation.org
>> Cc: linux-kernel@...r.kernel.org
>>
>> Reported-by: LABBE Corentin <clabbe@...libre.com>
>> Signed-off-by: Gonglei <arei.gonglei@...wei.com>
>> Signed-off-by: Longpeng(Mike) <longpeng2@...wei.com>
>> ---
>>   drivers/crypto/virtio/virtio_crypto_algs.c | 14 ++++++++++----
>>   1 file changed, 10 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/crypto/virtio/virtio_crypto_algs.c
>> b/drivers/crypto/virtio/virtio_crypto_algs.c
>> index 372babb44112..2fa1129f96d6 100644
>> --- a/drivers/crypto/virtio/virtio_crypto_algs.c
>> +++ b/drivers/crypto/virtio/virtio_crypto_algs.c
>> @@ -359,8 +359,14 @@ __virtio_crypto_skcipher_do_req(struct
>> virtio_crypto_sym_request *vc_sym_req,
>>       unsigned int num_out = 0, num_in = 0;
>>       int sg_total;
>>       uint8_t *iv;
>> +    struct scatterlist *sg;
>>         src_nents = sg_nents_for_len(req->src, req->cryptlen);
>> +    if (src_nents < 0) {
>> +        pr_err("Invalid number of src SG.\n");
>> +        return src_nents;
>> +    }
>> +
>>       dst_nents = sg_nents(req->dst);
>>         pr_debug("virtio_crypto: Number of sgs (src_nents: %d, dst_nents: %d)\n",
>> @@ -446,12 +452,12 @@ __virtio_crypto_skcipher_do_req(struct
>> virtio_crypto_sym_request *vc_sym_req,
>>       vc_sym_req->iv = iv;
>>         /* Source data */
>> -    for (i = 0; i < src_nents; i++)
>> -        sgs[num_out++] = &req->src[i];
>> +    for (sg = req->src, i = 0; sg && i < src_nents; sg = sg_next(sg), i++)
> 
> 
> Any reason sg is checked here?
> 
> I believe it should be checked in sg_nents_for_len().
> 
Do you means:
for (sg = req->src, i = 0; i < src_nents; sg = sg_next(sg), i++) ?

> 
>> +        sgs[num_out++] = sg;
>>         /* Destination data */
>> -    for (i = 0; i < dst_nents; i++)
>> -        sgs[num_out + num_in++] = &req->dst[i];
>> +    for (sg = req->dst, i = 0; sg && i < dst_nents; sg = sg_next(sg), i++)
>> +        sgs[num_out + num_in++] = sg;
> 
> 
> I believe sg should be checked in sg_nents().
>
How about
for (sg = req->dst; sg; sg = sg_next(sg)) ?

> Thanks
> 
> 
>>         /* Status */
>>       sg_init_one(&status_sg, &vc_req->status, sizeof(vc_req->status));
> 
> .
> 

-- 
---
Regards,
Longpeng(Mike)

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