Fix races around the access to ->s_options

Put generic_show_options read access to s_options under rcu_read_lock,
split save_mount_options() into "we are setting it the first time"
(uses in foo_fill_super()) and "we are relacing and freeing the old one",
synchronize_rcu() before kfree() in the latter.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 1 insertions, 2 deletions

diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
index d444fe0013a4..1215a4f50cd2 100644
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -1316,8 +1316,7 @@ static int reiserfs_remount(struct super_block *s, int *mount_flags, char *arg)
         }
 
 out_ok:
-        kfree(s->s_options);
-        s->s_options = new_opts;
+        replace_mount_options(s, new_opts);
         return 0;
 
 out_err: