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From: Robert Richter <rrichter@marvell.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>,
	Tony Luck <tony.luck@intel.com>,
	James Morse <james.morse@arm.com>,
	Aristeu Rozanski <aris@redhat.com>,
	Matthias Brugger <mbrugger@suse.com>,
	<linux-edac@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 01/10] EDAC/mc: Fix usage of snprintf() and dimm location setup
Date: Tue, 19 May 2020 11:27:48 +0200
Message-ID: <20200519092748.zalds3reudd22nky@rric.localdomain> (raw)
In-Reply-To: <20200422205243.GH26846@zn.tnic>

On 22.04.20 22:52:43, Borislav Petkov wrote:
> On Wed, Apr 22, 2020 at 01:58:05PM +0200, Robert Richter wrote:
> > The setup of the dimm->location may be incomplete in case writing to
> > dimm->label fails due to small buffer size. Fix this by iterating
> > through all existing layers.
> > 
> > Also, the return value of snprintf() can be higher than the number of
> > bytes written to the buffer in case it is to small. Fix usage of
> > snprintf() by either porting it to scnprintf() or fixing the handling
> > of the return code.
> > 
> > It is very unlikely the buffer is too small in practice, but fixing it
> > anyway.
> > 
> > Signed-off-by: Robert Richter <rrichter@marvell.com>
> > ---
> >  drivers/edac/edac_mc.c | 20 ++++++++++----------
> >  1 file changed, 10 insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
> > index 75ede27bdf6a..107d7c4de933 100644
> > --- a/drivers/edac/edac_mc.c
> > +++ b/drivers/edac/edac_mc.c
> > @@ -130,11 +130,11 @@ unsigned int edac_dimm_info_location(struct dimm_info *dimm, char *buf,
> >  		n = snprintf(p, len, "%s %d ",
> >  			      edac_layer_name[mci->layers[i].type],
> >  			      dimm->location[i]);
> > +		if (len <= n)
> > +			return count + len - 1;
> >  		p += n;
> >  		len -= n;
> >  		count += n;
> > -		if (!len)
> > -			break;
> >  	}
> >  
> >  	return count;
> > @@ -397,19 +397,19 @@ static int edac_mc_alloc_dimms(struct mem_ctl_info *mci)
> >  		 */
> >  		len = sizeof(dimm->label);
> >  		p = dimm->label;
> > -		n = snprintf(p, len, "mc#%u", mci->mc_idx);
> > +		n = scnprintf(p, len, "mc#%u", mci->mc_idx);
> >  		p += n;
> >  		len -= n;
> > +
> >  		for (layer = 0; layer < mci->n_layers; layer++) {
> > -			n = snprintf(p, len, "%s#%u",
> > -				     edac_layer_name[mci->layers[layer].type],
> > -				     pos[layer]);
> 
> The edac_layer_name[]'s are single words of a couple of letters and the
> pos is a number. The buffer we pass in is at least 80 chars and in one
> place even a PAGE_SIZE.
> 
> But in general, this is just silly with the buffers on stack and
> printing into them.
> 
> It would be much better to opencode that loop in
> edac_dimm_info_location() and simply dump those layer names at the call
> sites. And then kill that silly edac_dimm_info_location() function. See
> below for example.
> 
> And then since two call sites do edac_dbg(), you can put that in a
> function edac_dbg_dump_dimm_location() or so and call it and not care
> about any buffer lengths and s*printf's and so on.
> 
> Right?

The aim of this patch is just to fix snprintf() users. Anything else
would involve a larger cleanup. It is not only about edac_dbg(), there
are other users of edac_layer_name[] which implement similar things
that need to be looked at.

So I am dropping this patch from the series.

Thanks,

-Robert

  reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-22 11:58 [PATCH v2 00/10] EDAC/mc/ghes: Fixes, cleanup and reworks Robert Richter
2020-04-22 11:58 ` [PATCH v2 01/10] EDAC/mc: Fix usage of snprintf() and dimm location setup Robert Richter
2020-04-22 20:52   ` Borislav Petkov
2020-05-19  9:27     ` Robert Richter [this message]
2020-04-22 11:58 ` [PATCH v2 02/10] EDAC/mc: Use int type for parameters of edac_mc_alloc() Robert Richter
2020-04-23 17:49   ` Borislav Petkov
2020-05-19  9:33     ` Robert Richter
2020-04-22 11:58 ` [PATCH v2 03/10] EDAC/ghes: Remove unused members of struct ghes_edac_pvt, rename it to ghes_mci Robert Richter
2020-04-23 17:55   ` Borislav Petkov
2020-05-05  7:50     ` Robert Richter
2020-04-22 11:58 ` [PATCH v2 04/10] EDAC/ghes: Make SMBIOS handle private data to ghes Robert Richter
2020-04-24 12:12   ` kbuild test robot
2020-04-24 16:21   ` Borislav Petkov
2020-05-05 12:48     ` Robert Richter
2020-04-22 11:58 ` [PATCH v2 05/10] EDAC/ghes: Setup DIMM label from DMI and use it in error reports Robert Richter
2020-04-22 11:58 ` [PATCH v2 06/10] EDAC/ghes: Remove local variable rdr_mask in ghes_edac_dmidecode() Robert Richter
2020-04-27  7:08   ` Borislav Petkov
2020-04-27 17:24     ` Luck, Tony
2020-04-27 17:34       ` Borislav Petkov
2020-05-19  9:34         ` Robert Richter
2020-04-22 11:58 ` [PATCH v2 07/10] EDAC/ghes: Cleanup struct ghes_edac_dimm_fill, rename it to ghes_dimm_fill Robert Richter
2020-04-27 14:00   ` Borislav Petkov
2020-05-19  9:35     ` Robert Richter
2020-04-22 11:58 ` [PATCH v2 08/10] EDAC/ghes: Carve out MC device handling into separate functions Robert Richter
2020-04-27 16:38   ` Borislav Petkov
2020-05-06  8:45     ` Robert Richter
2020-05-11 13:32       ` Borislav Petkov
2020-05-19  9:57         ` Robert Richter
2020-04-22 11:58 ` [PATCH v2 09/10] EDAC/ghes: Have a separate code path for creating the fake MC Robert Richter
2020-04-22 11:58 ` [PATCH v2 10/10] EDAC/ghes: Carve out code into ghes_edac_register_{one,fake}() Robert Richter
2020-05-06  8:53 ` [PATCH v2 00/10] EDAC/mc/ghes: Fixes, cleanup and reworks Robert Richter

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