linux-kernel - Re: [PATCH] remoteproc: qcom_q6v5_mss: Validate p

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Date:   Wed, 13 Jan 2021 16:03:59 -0600
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:     Andy Gross <agross@...nel.org>, Ohad Ben-Cohen <ohad@...ery.com>,
        Sibi Sankar <sibis@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, linux-remoteproc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] remoteproc: qcom_q6v5_mss: Validate p_filesz in ELF
 loader

On Wed 13 Jan 15:22 CST 2021, Mathieu Poirier wrote:

> Hi Bjorn,
> 
> On Thu, Jan 07, 2021 at 03:50:53PM -0800, Bjorn Andersson wrote:
> > Analog to the issue in the common mdt_loader code the MSS ELF loader
> > does not validate that p_filesz bytes will fit in the memory region and
> > that the loaded segments are not truncated. Fix this in the same way
> > as proposed for the mdt_loader.
> > 
> > Fixes: 135b9e8d1cd8 ("remoteproc: qcom_q6v5_mss: Validate modem blob firmware size before load")
> > Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> > ---
> >  drivers/remoteproc/qcom_q6v5_mss.c | 17 +++++++++++++++++
> >  1 file changed, 17 insertions(+)
> > 
> > diff --git a/drivers/remoteproc/qcom_q6v5_mss.c b/drivers/remoteproc/qcom_q6v5_mss.c
> > index 66106ba25ba3..2b59e0cbdce1 100644
> > --- a/drivers/remoteproc/qcom_q6v5_mss.c
> > +++ b/drivers/remoteproc/qcom_q6v5_mss.c
> > @@ -1210,6 +1210,14 @@ static int q6v5_mpss_load(struct q6v5 *qproc)
> >  			goto release_firmware;
> >  		}
> >  
> > +		if (phdr->p_filesz > phdr->p_memsz) {
> > +			dev_err(qproc->dev,
> > +				"refusing to load segment %d with p_filesz > p_memsz\n",
> > +				i);
> > +			ret = -EINVAL;
> > +			break;
> 
> Based on the error handling for the above and below conditions, I would have
> expected a "goto release_firmware" rather than a "break".
> 

You're certainly right!

Yet another reason for the duplication between this function, the
mdt_loader and the remoteproc_elf_loader is a bad idea - still not sure
how to refactor any one of them to fit the three.

Thank you,
Bjorn

> > +		}
> > +
> >  		ptr = memremap(qproc->mpss_phys + offset, phdr->p_memsz, MEMREMAP_WC);
> >  		if (!ptr) {
> >  			dev_err(qproc->dev,
> > @@ -1241,6 +1249,15 @@ static int q6v5_mpss_load(struct q6v5 *qproc)
> >  				goto release_firmware;
> >  			}
> >  
> > +			if (seg_fw->size != phdr->p_filesz) {
> > +				dev_err(qproc->dev,
> > +					"failed to load segment %d from truncated file %s\n",
> > +					i, fw_name);
> > +				ret = -EINVAL;
> > +				memunmap(ptr);
> > +				break;
> 
> Same here.
> 
> > +			}
> > +
> >  			release_firmware(seg_fw);
> >  		}
> 
> Thanks,
> Mathieu
> 
> >  
> > -- 
> > 2.29.2
> >