Re: [RFC PATCH 1/2] crypto: Fix -Wstringop-truncation warnings

[Max Filippov]

On Fri, Jun 22, 2018 at 7:07 PM, Stafford Horne <shorne@xxxxxxxxx> wrote:
> As of GCC 9.0.0 the build is reporting warnings like:
>
>     crypto/ablkcipher.c: In function âcrypto_ablkcipher_reportâ:
>     crypto/ablkcipher.c:374:2: warning: âstrncpyâ specified bound 64 equals destination size [-Wstringop-truncation]
>       strncpy(rblkcipher.geniv, alg->cra_ablkcipher.geniv ?: "<default>",
>       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>        sizeof(rblkcipher.geniv));
>        ~~~~~~~~~~~~~~~~~~~~~~~~~
>
> This means the strnycpy might create a non null terminated string.  Fix this by
> limiting the size of the string copy to include the null terminator.

That could work if the destination buffer was zero-initialized,
but it's allocated on stack and is not initialized.
Replacing strncpy with strlcpy without changing its arguments
should do the right thing.

-- 
Thanks.
-- Max