Re: [PATCH v2 2/2] EDAC: Fix sysfs dimm_label store operation

[Toshi Kani <toshi.kani@hpe.com>]

On Thu, 2015-09-24 at 21:15 +0200, Borislav Petkov wrote:
> On Thu, Sep 24, 2015 at 01:06:04PM -0600, Toshi Kani wrote:
> > edac-utils(1) checks empty labels and shows them as "ch%d" [1].  So,
> > I think empty labels are supported today, and using 'echo "" >' seems
> > to be a legitimate way to set them empty if desired.
> 
> What would be a sane use case to set a DIMM label to an empty string?

Well, I guess there isn't a sane use case for it... :-)

Attached is a patch (on top of patch 2/2) to disallow an empty string.
I prefer to make it as a separate patch in case someone comes up with
a valid use-case for it.

Thanks,
-Toshi

====
Subject: [PATCH] EDAC: Fail empty string to sysfs dimm_label store

Updating dimm_label to an empty string does not make much sense.
Change the sysfs dimm_label store option to fail a request when
an input string is empty.

Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
---
 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 5252fb9..72ba530 100644
--- a/drivers/edac/edac_mc_sysfs.c
+++ b/drivers/edac/edac_mc_sysfs.c
@@ -248,7 +248,7 @@ static ssize_t channel_dimm_label_store(struct device *dev,
 	if (data[count - 1] == '\0' || data[count - 1] == '\n')
 		copy_count -= 1;
 
-	if (copy_count >= sizeof(rank->dimm->label))
+	if (copy_count == 0 || copy_count >= sizeof(rank->dimm->label))
 		return -EINVAL;
 
 	strncpy(rank->dimm->label, data, copy_count);
@@ -509,7 +509,7 @@ static ssize_t dimmdev_label_store(struct device *dev,
 	if (data[count - 1] == '\0' || data[count - 1] == '\n')
 		copy_count -= 1;
 
-	if (copy_count >= sizeof(dimm->label))
+	if (copy_count == 0 || copy_count >= sizeof(dimm->label))
 		return -EINVAL;
 
 	strncpy(dimm->label, data, copy_count);