[PATCH 4.9 085/271] fs/nfs: Fix nfs_parse_devname to not modify its argument

[Greg Kroah-Hartman]

From: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>

[ Upstream commit 40cc394be1aa18848b8757e03bd8ed23281f572e ]

In the rare and unsupported case of a hostname list nfs_parse_devname
will modify dev_name.  There is no need to modify dev_name as the all
that is being computed is the length of the hostname, so the computed
length can just be shorted.

Fixes: dc04589827f7 ("NFS: Use common device name parsing logic for NFSv4 and NFSv2/v3")
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/nfs/super.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 42c31587a936c..4c21e572f2d9e 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -1928,7 +1928,7 @@ static int nfs_parse_devname(const char *dev_name,
 		/* kill possible hostname list: not supported */
 		comma = strchr(dev_name, ',');
 		if (comma != NULL && comma < end)
-			*comma = 0;
+			len = comma - dev_name;
 	}
 
 	if (len > maxnamlen)
-- 
2.20.1