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From:   Shyam Prasad N <nspmangalore@gmail.com>
Date:   Tue, 23 May 2023 22:00:55 +0530
Message-ID: <CANT5p=r7usL_YOBxRoiVCrZpZr2+-FLjs1Jg_T6R5==HJQ0epg@mail.gmail.com>
Subject: Re: [PATCH v2] cifs: Fix cifs_limit_bvec_subset() to correctly check
 the maxmimum size
To:     David Howells <dhowells@redhat.com>
Cc:     Shyam Prasad N <sprasad@microsoft.com>,
        Steve French <smfrench@gmail.com>,
        Rohith Surabattula <rohiths.msft@gmail.com>,
        Paulo Alcantara <pc@manguebit.com>,
        Tom Talpey <tom@talpey.com>, Jeff Layton <jlayton@kernel.org>,
        linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org
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On Tue, May 23, 2023 at 6:24=E2=80=AFPM David Howells <dhowells@redhat.com>=
 wrote:
>
> Fix cifs_limit_bvec_subset() so that it limits the span to the maximum
> specified and won't return with a size greater than max_size.
>
> Fixes: d08089f649a0 ("cifs: Change the I/O paths to use an iterator rathe=
r than a page list")
> Reported-by: Shyam Prasad N <sprasad@microsoft.com>
> Signed-off-by: David Howells <dhowells@redhat.com>
> cc: Steve French <smfrench@gmail.com>
> cc: Rohith Surabattula <rohiths.msft@gmail.com>
> cc: Paulo Alcantara <pc@manguebit.com>
> cc: Tom Talpey <tom@talpey.com>
> cc: Jeff Layton <jlayton@kernel.org>
> cc: linux-cifs@vger.kernel.org
> cc: linux-fsdevel@vger.kernel.org
> ---
>  fs/cifs/file.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index ba7f2e09d6c8..df88b8c04d03 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -3353,9 +3353,10 @@ static size_t cifs_limit_bvec_subset(const struct =
iov_iter *iter, size_t max_siz
>         while (n && ix < nbv) {
>                 len =3D min3(n, bvecs[ix].bv_len - skip, max_size);
>                 span +=3D len;
> +               max_size -=3D len;
>                 nsegs++;
>                 ix++;
> -               if (span >=3D max_size || nsegs >=3D max_segs)
> +               if (max_size =3D=3D 0 || nsegs >=3D max_segs)
>                         break;
>                 skip =3D 0;
>                 n -=3D len;
>

Looks good to me.

--=20
Regards,
Shyam