[PATCH v2 1/2] EDAC: Fix sysfs dimm_label show operation

From: Toshi Kani
Date: Tue Sep 22 2015 - 11:01:33 EST


After 'commit 7d375bffa524 ("sb_edac: Fix support for systems with
two home agents per socket")', sysfs "dimm_label" and "chX_dimm_label"
show their label string without a newline "\n" at the end.

[root@orange ~]# cat /sys/bus/mc0/devices/dimm0/dimm_label
CPU_SrcID#0_Ha#0_Chan#0_DIMM#0[root@orange ~]#

[root@orange ~]# cat /sys/devices/system/edac/mc/mc0/csrow0/ch0_dimm_label
CPU_SrcID#0_Ha#0_Chan#0_DIMM#0[root@orange ~]#

The label strings now have 31 characters, which are the same as
EDAC_MC_LABEL_LEN. Since the snprintf()s in channel_dimm_label_show()
and dimmdev_label_show() limit the whole length by EDAC_MC_LABEL_LEN,
the newline in the format "%s\n" is ignored.

[root@orange ~]# od -bc /sys/bus/mc0/devices/dimm0/dimm_label
0000000 103 120 125 137 123 162 143 111 104 043 060 137 110 141 043 060
C P U _ S r c I D # 0 _ H a # 0
0000020 137 103 150 141 156 043 060 137 104 111 115 115 043 060 000
_ C h a n # 0 _ D I M M # 0 \0
0000037

Fix it by using 'sizeof(dimm->label) + 1' as the whole length in
the snprintf()s in channel_dimm_label_show() and dimmdev_label_show().

Reported-by: Robert Elliott <elliott@xxxxxxx>
Signed-off-by: Toshi Kani <toshi.kani@xxxxxxx>
Acked-by: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Doug Thompson <dougthompson@xxxxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Robert Elliott <elliott@xxxxxxx>
---
drivers/edac/edac_mc_sysfs.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/edac/edac_mc_sysfs.c b/drivers/edac/edac_mc_sysfs.c
index 33df7d9..8983755 100644
--- a/drivers/edac/edac_mc_sysfs.c
+++ b/drivers/edac/edac_mc_sysfs.c
@@ -229,7 +229,7 @@ static ssize_t channel_dimm_label_show(struct device *dev,
if (!rank->dimm->label[0])
return 0;

- return snprintf(data, EDAC_MC_LABEL_LEN, "%s\n",
+ return snprintf(data, sizeof(rank->dimm->label) + 1, "%s\n",
rank->dimm->label);
}

@@ -485,7 +485,7 @@ static ssize_t dimmdev_label_show(struct device *dev,
if (!dimm->label[0])
return 0;

- return snprintf(data, EDAC_MC_LABEL_LEN, "%s\n", dimm->label);
+ return snprintf(data, sizeof(dimm->label) + 1, "%s\n", dimm->label);
}

static ssize_t dimmdev_label_store(struct device *dev,
--
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