linux-kernel - Re: [PATCH] csiostor: Avoid content leaks and casts

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Date:   Tue, 23 May 2017 15:00:26 +0530
From:   Varun Prakash <varun@...lsio.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        "James E.J. Bottomley" <jejb@...ux.vnet.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        Daniel Micay <danielmicay@...il.com>
Subject: Re: [PATCH] csiostor: Avoid content leaks and casts

On Mon, May 22, 2017 at 09:29:41AM -0700, Kees Cook wrote:
> On Mon, May 22, 2017 at 8:05 AM, Varun Prakash <varun@...lsio.com> wrote:
> > On Tue, May 09, 2017 at 03:34:44PM -0700, Kees Cook wrote:
> >> When copying attributes, the len argument was padded out and the resulting
> >> memcpy() would copy beyond the end of the source buffer.  Avoid this,
> >> and use size_t for val_len to avoid all the casts. Similarly, avoid source
> >> buffer casts and use void *.
> >>
> >> Additionally enforces val_len can be represented by u16 and that
> >> the DMA buffer was not overflowed. Fixes the size of mfa, which is not
> >> FC_FDMI_PORT_ATTR_MAXFRAMESIZE_LEN (but it will be padded up to 4). This
> >> was noticed by the future CONFIG_FORTIFY_SOURCE checks.
> >>
> >> Cc: Daniel Micay <danielmicay@...il.com>
> >> Signed-off-by: Kees Cook <keescook@...omium.org>
> >> ---
> >>  drivers/scsi/csiostor/csio_lnode.c | 43 +++++++++++++++++++++++---------------
> >>  1 file changed, 26 insertions(+), 17 deletions(-)
> >>
> >> diff --git a/drivers/scsi/csiostor/csio_lnode.c b/drivers/scsi/csiostor/csio_lnode.c
> >> index c00b2ff72b55..be5ee2d37815 100644
> >> --- a/drivers/scsi/csiostor/csio_lnode.c
> >> +++ b/drivers/scsi/csiostor/csio_lnode.c
> >> @@ -238,14 +238,23 @@ csio_osname(uint8_t *buf, size_t buf_len)
> >>  }
> >>
> >
> >
> >>
> >>       csio_append_attrib(&pld, FC_FDMI_HBA_ATTR_MAXCTPAYLOAD,
> >> -                        (uint8_t *)&maxpayload,
> >> -                        FC_FDMI_HBA_ATTR_MAXCTPAYLOAD_LEN);
> >> +                        &maxpayload, FC_FDMI_HBA_ATTR_MAXCTPAYLOAD_LEN);
> >>       len = (uint32_t)(pld - (uint8_t *)cmd);
> >>       numattrs++;
> >>       attrib_blk->numattrs = htonl(numattrs);
> >> @@ -1794,6 +1801,8 @@ csio_ln_mgmt_submit_req(struct csio_ioreq *io_req,
> >>       struct csio_mgmtm *mgmtm = csio_hw_to_mgmtm(hw);
> >>       int rv;
> >>
> >> +     BUG_ON(pld_len > pld->len);
> >> +
> >
> > I think WARN_ON() is better than BUG_ON() in this case
> >
> >         if (WARN_ON(pld_len > pld->len))
> >                 return -EINVAL;
> >
> >>       io_req->io_cbfn = io_cbfn;      /* Upper layer callback handler */
> >>       io_req->fw_handle = (uintptr_t) (io_req);
> >>       io_req->eq_idx = mgmtm->eq_idx;
> 
> I chose BUG_ON here because the damage has already been done. If this
> assertion is hit, the heap buffers have already been overrun. This
> isn't a state we should only warn about...
> 

Ok.

Acked-by: Varun Prakash <varun@...lsio.com>