On 16/07/2020 16:56, Ard Biesheuvel wrote:
> On Thu, 16 Jul 2020 at 18:29, Colin King <colin.king@xxxxxxxxxxxxx> wrote:
>>
>> From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>>
>> There is a memcpy that performs a potential overlapped memory copy
>> from source b to destination b + 1. Fix this by using the safer
>> memmove instead.
>>
>> Addresses-Coverity: ("Overlapping buffer in memory copy")
>> Fixes: 8083b1bf8163 ("crypto: xts - add support for ciphertext stealing")
>> Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>> ---
>> crypto/xts.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/crypto/xts.c b/crypto/xts.c
>> index 3565f3b863a6..fa3e6e7b7043 100644
>> --- a/crypto/xts.c
>> +++ b/crypto/xts.c
>> @@ -169,7 +169,7 @@ static int cts_final(struct skcipher_request *req,
>> offset - XTS_BLOCK_SIZE);
>>
>> scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
>> - memcpy(b + 1, b, tail);
>> + memmove(b + 1, b, tail);
>
> This is a false positive: tail is guaranteed to be smaller than
> sizeof(*b), so memmove() is unnecessary here.
>
> If changing to memcpy(&b[1], &b[0], tail) makes the warning go away, i
> am fine with it, but otherwise we should just leave it as is.
In that case, just leave it as is. Apologies for the noise.
Colin
>
>
>> scatterwalk_map_and_copy(b, req->src, offset, tail, 0);
>>
>> le128_xor(b, &rctx->t, b);
>> --
>> 2.27.0
>>
