linux-kernel - [PATCH v3 06/10] EDAC/mc: Report "unknown memory" on too many DIMM labels found

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Date:   Thu, 23 Jan 2020 09:03:00 +0000
From:   Robert Richter <rrichter@...vell.com>
To:     Borislav Petkov <bp@...en8.de>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Tony Luck <tony.luck@...el.com>
CC:     James Morse <james.morse@....com>,
        Aristeu Rozanski <aris@...hat.com>,
        Robert Richter <rrichter@...vell.com>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH v3 06/10] EDAC/mc: Report "unknown memory" on too many DIMM
 labels found

There is a limitation to report only EDAC_MAX_LABELS in e->label of
the error descriptor. This is to prevent a possible string overflow.
Current implementation falls back to "any memory" in this case and
also stops all further processing to find a unique row and channel of
the possible error location. Reporting "any memory" is wrong as the
memory controller reported an error location for one of the layers.
Instead, report "unknown memory" and also do not break early in the
loop to further check row and channel for uniqueness.

Signed-off-by: Robert Richter <rrichter@...vell.com>
Acked-by: Aristeu Rozanski <aris@...hat.com>
---
 drivers/edac/edac_mc.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
index e75cb7a9c454..aa94152777fe 100644
--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@ -1245,20 +1245,21 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type,
 		 * channel/memory controller/...  may be affected.
 		 * Also, don't show errors for empty DIMM slots.
 		 */
-		if (!e->enable_per_layer_report || !dimm->nr_pages)
+		if (!dimm->nr_pages)
 			continue;
 
-		if (n_labels >= EDAC_MAX_LABELS) {
-			e->enable_per_layer_report = false;
-			break;
-		}
 		n_labels++;
-		if (p != e->label) {
-			strcpy(p, OTHER_LABEL);
-			p += strlen(OTHER_LABEL);
+		if (n_labels > EDAC_MAX_LABELS) {
+			p = e->label;
+			*p = '\0';
+		} else {
+			if (p != e->label) {
+				strcpy(p, OTHER_LABEL);
+				p += strlen(OTHER_LABEL);
+			}
+			strcpy(p, dimm->label);
+			p += strlen(p);
 		}
-		strcpy(p, dimm->label);
-		p += strlen(p);
 
 		/*
 		 * get csrow/channel of the DIMM, in order to allow
-- 
2.20.1