audit: Fix sleep in atomic

Audit tree code was happily adding new notification marks while holding
spinlocks. Since fsnotify_add_mark() acquires group->mark_mutex this can
lead to sleeping while holding a spinlock, deadlocks due to lock
inversion, and probably other fun. Fix the problem by acquiring
group->mark_mutex earlier.

CC: Paul Moore <paul@paul-moore.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paul Moore <paul@paul-moore.com>

1 files changed, 14 insertions, 4 deletions

diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
index b4b58400531f..862969014cf6 100644
--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -231,9 +231,11 @@ static void untag_chunk(struct node *p)
         if (size)
                 new = alloc_chunk(size);
 
+        mutex_lock(&entry->group->mark_mutex);
         spin_lock(&entry->lock);
         if (chunk->dead || !entry->inode) {
                 spin_unlock(&entry->lock);
+                mutex_unlock(&entry->group->mark_mutex);
                 if (new)
                         free_chunk(new);
                 goto out;
@@ -251,6 +253,7 @@ static void untag_chunk(struct node *p)
                 list_del_rcu(&chunk->hash);
                 spin_unlock(&hash_lock);
                 spin_unlock(&entry->lock);
+                mutex_unlock(&entry->group->mark_mutex);
                 fsnotify_destroy_mark(entry, audit_tree_group);
                 goto out;
         }
@@ -258,8 +261,8 @@ static void untag_chunk(struct node *p)
         if (!new)
                 goto Fallback;
 
-        if (fsnotify_add_mark(&new->mark,
-                              entry->group, entry->inode, NULL, 1)) {
+        if (fsnotify_add_mark_locked(&new->mark, entry->group, entry->inode,
+                                     NULL, 1)) {
                 fsnotify_put_mark(&new->mark);
                 goto Fallback;
         }
@@ -293,6 +296,7 @@ static void untag_chunk(struct node *p)
                 owner->root = new;
         spin_unlock(&hash_lock);
         spin_unlock(&entry->lock);
+        mutex_unlock(&entry->group->mark_mutex);
         fsnotify_destroy_mark(entry, audit_tree_group);
         fsnotify_put_mark(&new->mark);  /* drop initial reference */
         goto out;
@@ -309,6 +313,7 @@ Fallback:
         put_tree(owner);
         spin_unlock(&hash_lock);
         spin_unlock(&entry->lock);
+        mutex_unlock(&entry->group->mark_mutex);
 out:
         fsnotify_put_mark(entry);
         spin_lock(&hash_lock);
@@ -386,18 +391,21 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
 
         chunk_entry = &chunk->mark;
 
+        mutex_lock(&old_entry->group->mark_mutex);
         spin_lock(&old_entry->lock);
         if (!old_entry->inode) {
                 /* old_entry is being shot, lets just lie */
                 spin_unlock(&old_entry->lock);
+                mutex_unlock(&old_entry->group->mark_mutex);
                 fsnotify_put_mark(old_entry);
                 free_chunk(chunk);
                 return -ENOENT;
         }
 
-        if (fsnotify_add_mark(chunk_entry,
-                              old_entry->group, old_entry->inode, NULL, 1)) {
+        if (fsnotify_add_mark_locked(chunk_entry, old_entry->group,
+                                     old_entry->inode, NULL, 1)) {
                 spin_unlock(&old_entry->lock);
+                mutex_unlock(&old_entry->group->mark_mutex);
                 fsnotify_put_mark(chunk_entry);
                 fsnotify_put_mark(old_entry);
                 return -ENOSPC;
@@ -413,6 +421,7 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
                 chunk->dead = 1;
                 spin_unlock(&chunk_entry->lock);
                 spin_unlock(&old_entry->lock);
+                mutex_unlock(&old_entry->group->mark_mutex);
 
                 fsnotify_destroy_mark(chunk_entry, audit_tree_group);
 
@@ -445,6 +454,7 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
         spin_unlock(&hash_lock);
         spin_unlock(&chunk_entry->lock);
         spin_unlock(&old_entry->lock);
+        mutex_unlock(&old_entry->group->mark_mutex);
         fsnotify_destroy_mark(old_entry, audit_tree_group);
         fsnotify_put_mark(chunk_entry); /* drop initial reference */
         fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */