[PATCH] fs/nfs: Fix nfs_parse_devname to not modify it's argument

[PATCH] fs/nfs: Fix nfs_parse_devname to not modify it's argument

[Eric W. Biederman]

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@xmission.com>
---
 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 22ce3c8a2f46..35af005af748 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -1914,7 +1914,7 @@ 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)
-- 
2.17.1

Re: [PATCH] fs/nfs: Fix nfs_parse_devname to not modify it's argument

[Trond Myklebust]

On Wed, 2019-01-30 at 07:58 -0600, Eric W. Biederman wrote:
> 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@xmission.com>

Thanks Eric! Applied to my linux-next branch for inclusion in the 5.1
merge window.

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com