linux-hardening - Re: [PATCH] drivers/bluetooth: Remove all strcpy() uses

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Date:   Sun, 18 Jul 2021 17:12:55 +0100
From:   Adam Sampson <ats@...og.org>
To:     Len Baker <len.baker@....com>
Cc:     Kees Cook <keescook@...omium.org>,
        Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org
Subject: Re: [PATCH] drivers/bluetooth: Remove all strcpy() uses

Len Baker <len.baker@....com> writes:

> strcpy() performs no bounds checking on the destination buffer. This
> could result in linear overflows beyond the end of the buffer, leading
> to all kinds of misbehaviors. The safe replacement is strscpy() but in
> this case it is better to use the scnprintf to simplify the arithmetic.
>
> This is a previous step in the path to remove the strcpy() function
> entirely from the kernel.
>
> Signed-off-by: Len Baker <len.baker@....com>
> ---
>  drivers/bluetooth/btmrvl_sdio.c | 27 +++++++++++++--------------
>  1 file changed, 13 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/bluetooth/btmrvl_sdio.c b/drivers/bluetooth/btmrvl_sdio.c
> index cddd350beba3..d6674b367e05 100644
> --- a/drivers/bluetooth/btmrvl_sdio.c
> +++ b/drivers/bluetooth/btmrvl_sdio.c
> @@ -1350,6 +1350,7 @@ static void btmrvl_sdio_coredump(struct device *dev)
>  	u8 *dbg_ptr, *end_ptr, *fw_dump_data, *fw_dump_ptr;
[...]
> +			size += scnprintf(fw_dump_ptr + size,
> +					  sizeof(fw_dump_ptr) - size,
[...]
> +			size += scnprintf(fw_dump_ptr + size,
> +					  sizeof(fw_dump_ptr) - size,

sizeof(fw_dump_ptr) there looks wrong -- you want the size of the buffer
it points to (fw_dump_len + 1)?

Thanks,

-- 
Adam Sampson <ats@...og.org>                         <http://offog.org/>