GFS2: GFS2 will panic if you misspell any mount options

The gfs2 superblock pointer is NULL after a failed mount. When control
eventually goes to gfs2_kill_sb, we dereference this NULL pointer. This
patch ensures that the gfs2 superblock pointer is not NULL before being
dereferenced in gfs2_kill_sb.

Signed-off-by:   Abhijith Das <adas@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index a6225cce2cbc70181d6248799aac2a6383fb3bb6..ae35f097aa6a303bf0ebbd40078bb968be940b3c 100644 (file)
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -1237,14 +1237,17 @@ static int gfs2_get_sb_meta(struct file_system_type *fs_type, int flags,
 static void gfs2_kill_sb(struct super_block *sb)
 {
        struct gfs2_sbd *sdp = sb->s_fs_info;
-       gfs2_meta_syncfs(sdp);
-       dput(sdp->sd_root_dir);
-       dput(sdp->sd_master_dir);
-       sdp->sd_root_dir = NULL;
-       sdp->sd_master_dir = NULL;
+       if (sdp) {
+               gfs2_meta_syncfs(sdp);
+               dput(sdp->sd_root_dir);
+               dput(sdp->sd_master_dir);
+               sdp->sd_root_dir = NULL;
+               sdp->sd_master_dir = NULL;
+       }
        shrink_dcache_sb(sb);
        kill_block_super(sb);
-       gfs2_delete_debugfs_file(sdp);
+       if (sdp)
+               gfs2_delete_debugfs_file(sdp);
 }
 
 struct file_system_type gfs2_fs_type = {