From: Borislav Petkov <bp@alien8.de> To: Robert Richter <rrichter@marvell.com> 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: Wed, 22 Apr 2020 22:52:43 +0200 Message-ID: <20200422205243.GH26846@zn.tnic> (raw) In-Reply-To: <20200422115814.22205-2-rrichter@marvell.com> 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? --- diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c index 422120793a6b..7c04ef0c3536 100644 --- a/drivers/edac/edac_mc.c +++ b/drivers/edac/edac_mc.c @@ -91,16 +91,23 @@ static void edac_mc_dump_channel(struct rank_info *chan) static void edac_mc_dump_dimm(struct dimm_info *dimm) { - char location[80]; + struct mem_ctl_info *mci = dimm->mci; + int i; if (!dimm->nr_pages) return; - edac_dimm_info_location(dimm, location, sizeof(location)); + edac_dbg(4, "%s%i: ", dimm->mci->csbased ? "rank" : "dimm", dimm->idx); + + for (i = 0; i < mci->n_layers; i++) + edac_dbg(4, "%s %d ", + edac_layer_name[mci->layers[i].type], + dimm->location[i]); + + edac_dbg(4, "mapped as virtual row %d, chan %d\n", + dimm->csrow, dimm->cschannel); - edac_dbg(4, "%s%i: %smapped as virtual row %d, chan %d\n", - dimm->mci->csbased ? "rank" : "dimm", - dimm->idx, location, dimm->csrow, dimm->cschannel); edac_dbg(4, " dimm = %p\n", dimm); edac_dbg(4, " dimm->label = '%s'\n", dimm->label); edac_dbg(4, " dimm->nr_pages = 0x%x\n", dimm->nr_pages); -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette
next prev parent 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 [this message] 2020-05-19 9:27 ` Robert Richter 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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