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audit: Fix sleep in atomic

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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>
This commit is contained in:
Jan Kara 2016-12-14 14:40:05 +01:00 committed by Paul Moore
parent e3ba730702
commit be29d20f3f
1 changed files with 14 additions and 4 deletions
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18
kernel/audit_tree.c
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@ -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 @@ static void untag_chunk(struct node *p)
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 */