From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 03 Jan 2022 17:17:06 GMT
Subject: Re: [PATCH v2] gpg-interface: trim CR from ssh-keygen
Message-ID: <CAPig+cS6h6o2_dJAZC1M1Ace29bN2mhPgaEtTWtj3oXfcHq9cA@mail.gmail.com>
In-Reply-To: <20220103095337.600536-1-fs@gigacodes.de>

On Mon, Jan 3, 2022 at 9:24 AM Fabian Stelzer <fs@gigacodes.de> wrote:
> We need to trim \r from the output of 'ssh-keygen -Y find-principals' on
> Windows, or we end up calling 'ssh-keygen -Y verify' with a bogus signer
> identity. ssh-keygen.c:2841 contains a call to puts(3), which confirms
> this hypothesis. Signature verification passes with the fix.
>
> Helped-by: Pedro Martelletto <pedro@yubico.com>
> Signed-off-by: Fabian Stelzer <fs@gigacodes.de>
> ---
> diff --git a/gpg-interface.c b/gpg-interface.c
> @@ -509,7 +509,10 @@ static int verify_ssh_signed_buffer(struct signature_check *sigc,
> -                       trust_size = strcspn(line, "\n");
> +                       trust_size = strcspn(line, "\n"); /* truncate at LF */
> +                       if (trust_size && trust_size != strlen(line) &&
> +                           line[trust_size - 1] == '\r')
> +                               trust_size--; /* the LF was part of CRLF at the end */

I may be misunderstanding, but isn't the strlen() unnecessary?

    if (trust_size && line[trust_size] &&
        line[trust_size - 1] == '\r')
            trust_size--;