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From:   "T.J. Mercier" <tjmercier@google.com>
Date:   Fri, 17 Nov 2023 10:50:21 -0800
Message-ID: <CABdmKX1oNw+quAd+ALcgGoz-PPsvy=O6YM4f2_SmP+dQBddzAA@mail.gmail.com>
Subject: Re: [PATCH] dma-buf: Replace strlcpy() with strscpy()
To:     Kees Cook <keescook@chromium.org>
Cc:     Sumit Semwal <sumit.semwal@linaro.org>,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        Azeem Shaikh <azeemshaikh38@gmail.com>,
        linaro-mm-sig@lists.linaro.org, linux-hardening@vger.kernel.org,
        =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>,
        linux-media@vger.kernel.org
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On Thu, Nov 16, 2023 at 11:14=E2=80=AFAM Kees Cook <keescook@chromium.org> =
wrote:
>
> strlcpy() reads the entire source buffer first. This read may exceed
> the destination size limit. This is both inefficient and can lead
> to linear read overflows if a source string is not NUL-terminated[1].
> Additionally, it returns the size of the source string, not the
> resulting size of the destination string. In an effort to remove strlcpy(=
)
> completely[2], replace strlcpy() here with strscpy().
>
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strl=
cpy [1]
> Link: https://github.com/KSPP/linux/issues/89 [2]
> Cc: Sumit Semwal <sumit.semwal@linaro.org>
> Cc: "Christian K=C3=B6nig" <christian.koenig@amd.com>
> Cc: Azeem Shaikh <azeemshaikh38@gmail.com>
> Cc: linux-media@vger.kernel.org
> Cc: dri-devel@lists.freedesktop.org
> Cc: linaro-mm-sig@lists.linaro.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: T.J. Mercier <tjmercier@google.com>

strscpy returns -E2BIG when it truncates / force null-terminates which
would provide the wrong argument for dynamic_dname, but
dma_buf_set_name{_user} makes sure we have a null-terminated string of
the appropriate maximum size in dmabuf->name.