GFS2: Fix use-after-free bug on umount

There was a use-after-free with the GFS2 super block during
umount. This patch moves almost all of the umount code from
->put_super into ->kill_sb, the only bit that cannot be moved
being the glock hash clearing which has to remain as ->put_super
due to umount ordering requirements. As a result its now obvious
that the kfree is the final operation, whereas before it was
hidden in ->put_super.

Also gfs2_jindex_free is then only referenced from a single file
so thats moved and marked static too.

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

6 files changed, 94 insertions, 114 deletions

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 6e298b070117..5eae62e7f778 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1547,8 +1547,9 @@ static void clear_glock(struct gfs2_glock *gl)
  * Called when unmounting the filesystem.
  */
 
-void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
+void gfs2_gl_hash_clear(struct super_block *sb)
 {
+        struct gfs2_sbd *sdp = sb->s_fs_info;
         unsigned long t;
         unsigned int x;
         int cont;
diff --git a/fs/gfs2/glock.h b/fs/gfs2/glock.h
index 543ec7ecfbda..ce54f338cff9 100644
--- a/fs/gfs2/glock.h
+++ b/fs/gfs2/glock.h
@@ -130,7 +130,7 @@ void gfs2_lvb_unhold(struct gfs2_glock *gl);
 
 void gfs2_glock_cb(void *cb_data, unsigned int type, void *data);
 void gfs2_reclaim_glock(struct gfs2_sbd *sdp);
-void gfs2_gl_hash_clear(struct gfs2_sbd *sdp);
+void gfs2_gl_hash_clear(struct super_block *sb);
 void gfs2_glock_finish_truncate(struct gfs2_inode *ip);
 
 int __init gfs2_glock_init(void);
diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index 4cae60f4a175..2e735bece6b9 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -705,6 +705,40 @@ static int gfs2_jindex_hold(struct gfs2_sbd *sdp, struct gfs2_holder *ji_gh)
         return error;
 }
 
+/**
+ * gfs2_jindex_free - Clear all the journal index information
+ * @sdp: The GFS2 superblock
+ *
+ */
+
+static void gfs2_jindex_free(struct gfs2_sbd *sdp)
+{
+        struct list_head list, *head;
+        struct gfs2_jdesc *jd;
+        struct gfs2_journal_extent *jext;
+
+        spin_lock(&sdp->sd_jindex_spin);
+        list_add(&list, &sdp->sd_jindex_list);
+        list_del_init(&sdp->sd_jindex_list);
+        sdp->sd_journals = 0;
+        spin_unlock(&sdp->sd_jindex_spin);
+
+        while (!list_empty(&list)) {
+                jd = list_entry(list.next, struct gfs2_jdesc, jd_list);
+                head = &jd->extent_list;
+                while (!list_empty(head)) {
+                        jext = list_entry(head->next,
+                                          struct gfs2_journal_extent,
+                                          extent_list);
+                        list_del(&jext->extent_list);
+                        kfree(jext);
+                }
+                list_del(&jd->jd_list);
+                iput(jd->jd_inode);
+                kfree(jd);
+        }
+}
+
 static int init_journal(struct gfs2_sbd *sdp, int undo)
 {
         struct inode *master = sdp->sd_master_dir->d_inode;
@@ -1203,7 +1237,7 @@ fail_sb:
 fail_locking:
         init_locking(sdp, &mount_gh, UNDO);
 fail_lm:
-        gfs2_gl_hash_clear(sdp);
+        gfs2_gl_hash_clear(sb);
         gfs2_lm_unmount(sdp);
         while (invalidate_inodes(sb))
                 yield();
@@ -1263,17 +1297,61 @@ 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;
-        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;
+
+        if (sdp == NULL) {
+                kill_block_super(sb);
+                return;
         }
-        shrink_dcache_sb(sb);
+        gfs2_meta_syncfs(sdp);
+        dput(sdp->sd_root_dir);
+        dput(sdp->sd_master_dir);
+        sdp->sd_root_dir = NULL;
+        sdp->sd_master_dir = NULL;
+
+        /*  Unfreeze the filesystem, if we need to  */
+        mutex_lock(&sdp->sd_freeze_lock);
+        if (sdp->sd_freeze_count)
+                gfs2_glock_dq_uninit(&sdp->sd_freeze_gh);
+        mutex_unlock(&sdp->sd_freeze_lock);
+
+        kthread_stop(sdp->sd_quotad_process);
+        kthread_stop(sdp->sd_logd_process);
+        kthread_stop(sdp->sd_recoverd_process);
+
+        if (!(sb->s_flags & MS_RDONLY)) {
+                int error = gfs2_make_fs_ro(sdp);
+                if (error)
+                        gfs2_io_error(sdp);
+        }
+
+        /* At this point, we're through modifying the disk */
+        gfs2_jindex_free(sdp);
+        gfs2_clear_rgrpd(sdp);
+        iput(sdp->sd_jindex);
+        iput(sdp->sd_inum_inode);
+        iput(sdp->sd_statfs_inode);
+        iput(sdp->sd_rindex);
+        iput(sdp->sd_quota_inode);
+
+        gfs2_glock_put(sdp->sd_rename_gl);
+        gfs2_glock_put(sdp->sd_trans_gl);
+
+        if (!sdp->sd_args.ar_spectator) {
+                gfs2_glock_dq_uninit(&sdp->sd_journal_gh);
+                gfs2_glock_dq_uninit(&sdp->sd_jinode_gh);
+                gfs2_glock_dq_uninit(&sdp->sd_ir_gh);
+                gfs2_glock_dq_uninit(&sdp->sd_sc_gh);
+                gfs2_glock_dq_uninit(&sdp->sd_qc_gh);
+                iput(sdp->sd_ir_inode);
+                iput(sdp->sd_sc_inode);
+                iput(sdp->sd_qc_inode);
+        }
+        gfs2_glock_dq_uninit(&sdp->sd_live_gh);
         kill_block_super(sb);
-        if (sdp)
-                gfs2_delete_debugfs_file(sdp);
+        gfs2_lm_unmount(sdp);
+        gfs2_sys_fs_del(sdp);
+        gfs2_delete_debugfs_file(sdp);
+        kfree(sdp);
 }
 
 struct file_system_type gfs2_fs_type = {
diff --git a/fs/gfs2/ops_super.c b/fs/gfs2/ops_super.c
index 08837a728635..bd08a0a8d9bf 100644
--- a/fs/gfs2/ops_super.c
+++ b/fs/gfs2/ops_super.c
@@ -95,7 +95,7 @@ do_flush:
  * Returns: errno
  */
 
-static int gfs2_make_fs_ro(struct gfs2_sbd *sdp)
+int gfs2_make_fs_ro(struct gfs2_sbd *sdp)
 {
         struct gfs2_holder t_gh;
         int error;
@@ -122,70 +122,6 @@ static int gfs2_make_fs_ro(struct gfs2_sbd *sdp)
 }
 
 /**
- * gfs2_put_super - Unmount the filesystem
- * @sb: The VFS superblock
- *
- */
-
-static void gfs2_put_super(struct super_block *sb)
-{
-        struct gfs2_sbd *sdp = sb->s_fs_info;
-        int error;
-
-        /*  Unfreeze the filesystem, if we need to  */
-
-        mutex_lock(&sdp->sd_freeze_lock);
-        if (sdp->sd_freeze_count)
-                gfs2_glock_dq_uninit(&sdp->sd_freeze_gh);
-        mutex_unlock(&sdp->sd_freeze_lock);
-
-        kthread_stop(sdp->sd_quotad_process);
-        kthread_stop(sdp->sd_logd_process);
-        kthread_stop(sdp->sd_recoverd_process);
-
-        if (!(sb->s_flags & MS_RDONLY)) {
-                error = gfs2_make_fs_ro(sdp);
-                if (error)
-                        gfs2_io_error(sdp);
-        }
-        /*  At this point, we're through modifying the disk  */
-
-        /*  Release stuff  */
-
-        iput(sdp->sd_jindex);
-        iput(sdp->sd_inum_inode);
-        iput(sdp->sd_statfs_inode);
-        iput(sdp->sd_rindex);
-        iput(sdp->sd_quota_inode);
-
-        gfs2_glock_put(sdp->sd_rename_gl);
-        gfs2_glock_put(sdp->sd_trans_gl);
-
-        if (!sdp->sd_args.ar_spectator) {
-                gfs2_glock_dq_uninit(&sdp->sd_journal_gh);
-                gfs2_glock_dq_uninit(&sdp->sd_jinode_gh);
-                gfs2_glock_dq_uninit(&sdp->sd_ir_gh);
-                gfs2_glock_dq_uninit(&sdp->sd_sc_gh);
-                gfs2_glock_dq_uninit(&sdp->sd_qc_gh);
-                iput(sdp->sd_ir_inode);
-                iput(sdp->sd_sc_inode);
-                iput(sdp->sd_qc_inode);
-        }
-
-        gfs2_glock_dq_uninit(&sdp->sd_live_gh);
-        gfs2_clear_rgrpd(sdp);
-        gfs2_jindex_free(sdp);
-        /*  Take apart glock structures and buffer lists  */
-        gfs2_gl_hash_clear(sdp);
-        /*  Unmount the locking protocol  */
-        gfs2_lm_unmount(sdp);
-
-        /*  At this point, we're through participating in the lockspace  */
-        gfs2_sys_fs_del(sdp);
-        kfree(sdp);
-}
-
-/**
  * gfs2_write_super
  * @sb: the superblock
  *
@@ -686,7 +622,7 @@ const struct super_operations gfs2_super_ops = {
         .destroy_inode          = gfs2_destroy_inode,
         .write_inode            = gfs2_write_inode,
         .delete_inode           = gfs2_delete_inode,
-        .put_super              = gfs2_put_super,
+        .put_super              = gfs2_gl_hash_clear,
         .write_super            = gfs2_write_super,
         .sync_fs                = gfs2_sync_fs,
         .write_super_lockfs     = gfs2_write_super_lockfs,
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 141b781f2fcc..f14658b20204 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -33,40 +33,6 @@
 #include "trans.h"
 #include "util.h"
 
-/**
- * gfs2_jindex_free - Clear all the journal index information
- * @sdp: The GFS2 superblock
- *
- */
-
-void gfs2_jindex_free(struct gfs2_sbd *sdp)
-{
-        struct list_head list, *head;
-        struct gfs2_jdesc *jd;
-        struct gfs2_journal_extent *jext;
-
-        spin_lock(&sdp->sd_jindex_spin);
-        list_add(&list, &sdp->sd_jindex_list);
-        list_del_init(&sdp->sd_jindex_list);
-        sdp->sd_journals = 0;
-        spin_unlock(&sdp->sd_jindex_spin);
-
-        while (!list_empty(&list)) {
-                jd = list_entry(list.next, struct gfs2_jdesc, jd_list);
-                head = &jd->extent_list;
-                while (!list_empty(head)) {
-                        jext = list_entry(head->next,
-                                          struct gfs2_journal_extent,
-                                          extent_list);
-                        list_del(&jext->extent_list);
-                        kfree(jext);
-                }
-                list_del(&jd->jd_list);
-                iput(jd->jd_inode);
-                kfree(jd);
-        }
-}
-
 static struct gfs2_jdesc *jdesc_find_i(struct list_head *head, unsigned int jid)
 {
         struct gfs2_jdesc *jd;
diff --git a/fs/gfs2/super.h b/fs/gfs2/super.h
index f6b8b00ad881..4d2492b3e7ef 100644
--- a/fs/gfs2/super.h
+++ b/fs/gfs2/super.h
@@ -25,8 +25,6 @@ static inline unsigned int gfs2_jindex_size(struct gfs2_sbd *sdp)
         return x;
 }
 
-void gfs2_jindex_free(struct gfs2_sbd *sdp);
-
 struct gfs2_jdesc *gfs2_jdesc_find(struct gfs2_sbd *sdp, unsigned int jid);
 int gfs2_jdesc_check(struct gfs2_jdesc *jd);
 
@@ -34,6 +32,7 @@ int gfs2_lookup_in_master_dir(struct gfs2_sbd *sdp, char *filename,
                               struct gfs2_inode **ipp);
 
 int gfs2_make_fs_rw(struct gfs2_sbd *sdp);
+int gfs2_make_fs_ro(struct gfs2_sbd *sdp);
 
 int gfs2_statfs_init(struct gfs2_sbd *sdp);
 void gfs2_statfs_change(struct gfs2_sbd *sdp,