btrfs: replace strncpy() with strscpy()

Using strncpy() on NUL-terminated strings are deprecated.  To avoid
possible forming of non-terminated string strscpy() should be used.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

CC: stable@vger.kernel.org # 4.9+
Signed-off-by: Artem Chernyshev <artem.chernyshev@red-soft.ru>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index bed74a3..4fd6b61 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2859,13 +2859,10 @@ static long btrfs_ioctl_dev_info(struct btrfs_fs_info *fs_info,
        di_args->bytes_used = btrfs_device_get_bytes_used(dev);
        di_args->total_bytes = btrfs_device_get_total_bytes(dev);
        memcpy(di_args->uuid, dev->uuid, sizeof(di_args->uuid));
-       if (dev->name) {
-               strncpy(di_args->path, btrfs_dev_name(dev),
-                               sizeof(di_args->path) - 1);
-               di_args->path[sizeof(di_args->path) - 1] = 0;
-       } else {
+       if (dev->name)
+               strscpy(di_args->path, btrfs_dev_name(dev), sizeof(di_args->path));
+       else
                di_args->path[0] = '\0';
-       }
 
 out:
        rcu_read_unlock();

diff --git a/fs/btrfs/rcu-string.h b/fs/btrfs/rcu-string.h
index 5c1a617..5c2b66d 100644 (file)
--- a/fs/btrfs/rcu-string.h
+++ b/fs/btrfs/rcu-string.h
@@ -18,7 +18,11 @@ static inline struct rcu_string *rcu_string_strdup(const char *src, gfp_t mask)
                                         (len * sizeof(char)), mask);
        if (!ret)
                return ret;
-       strncpy(ret->str, src, len);
+       /* Warn if the source got unexpectedly truncated. */
+       if (WARN_ON(strscpy(ret->str, src, len) < 0)) {
+               kfree(ret);
+               return NULL;
+       }
        return ret;
 }