Btrfs: NUL-terminate path buffer in DEV_INFO ioctl result

A device with name of length BTRFS_DEVICE_PATH_NAME_MAX or longer
would not be NUL-terminated in the DEV_INFO ioctl result buffer.

Signed-off-by: Jim Meyering <meyering@redhat.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 9ebb2c7145ad..3d8ab27622cd 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2263,10 +2263,12 @@ static long btrfs_ioctl_dev_info(struct btrfs_root *root, void __user *arg)
         di_args->bytes_used = dev->bytes_used;
         di_args->total_bytes = dev->total_bytes;
         memcpy(di_args->uuid, dev->uuid, sizeof(di_args->uuid));
-        if (dev->name)
+        if (dev->name) {
                 strncpy(di_args->path, dev->name, sizeof(di_args->path));
-        else
+                di_args->path[sizeof(di_args->path) - 1] = 0;
+        } else {
                 di_args->path[0] = '\0';
+        }
 
 out:
         if (ret == 0 && copy_to_user(arg, di_args, sizeof(*di_args)))