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References: <20210817102709.15046-1-len.baker@gmx.com> <87im03h9zb.fsf@cjr.nz>
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From:   Steve French <smfrench@gmail.com>
Date:   Tue, 17 Aug 2021 21:46:38 -0500
Message-ID: <CAH2r5mtKsjPesR6yBTO8RB=BFYc5Cb23OA_gEQyWMNrORXdavg@mail.gmail.com>
Subject: Re: [PATCH] CIFS: Fix a potencially linear read overflow
To:     Paulo Alcantara <pc@cjr.nz>
Cc:     Len Baker <len.baker@gmx.com>, Steve French <sfrench@samba.org>,
        Jeff Layton <jlayton@kernel.org>,
        Suresh Jayaraman <sjayaraman@suse.de>,
        CIFS <linux-cifs@vger.kernel.org>,
        samba-technical <samba-technical@lists.samba.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Kees Cook <keescook@chromium.org>,
        linux-hardening@vger.kernel.org
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Precedence: bulk

tentatively merged into cifs-2.6.git for-next pending testing

On Tue, Aug 17, 2021 at 7:29 PM Paulo Alcantara <pc@cjr.nz> wrote:
>
> Len Baker <len.baker@gmx.com> writes:
>
> > 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.
> >
> > Also, the strnlen() call does not avoid the read overflow in the strlcpy
> > function when a not NUL-terminated string is passed.
> >
> > So, replace this block by a call to kstrndup() that avoids this type of
> > overflow and does the same.
> >
> > Fixes: 066ce6899484d ("cifs: rename cifs_strlcpy_to_host and make it use new functions")
> > Signed-off-by: Len Baker <len.baker@gmx.com>
> > ---
> >  fs/cifs/cifs_unicode.c | 9 ++-------
> >  1 file changed, 2 insertions(+), 7 deletions(-)
>
> Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>


-- 
Thanks,

Steve