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@xxxxxxxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
kernel/audit_tree.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
index f3130eb0a4bd..156b6a93f4fc 100644
--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -231,6 +231,7 @@ 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);
@@ -258,7 +259,8 @@ 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;
}
@@ -309,6 +311,7 @@ static void untag_chunk(struct node *p)
spin_unlock(&hash_lock);
spin_unlock(&entry->lock);
out:
+ mutex_unlock(&entry->group->mark_mutex);
fsnotify_put_mark(entry);
spin_lock(&hash_lock);
}
@@ -385,17 +388,21 @@ 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;
@@ -411,6 +418,7 @@ 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);
@@ -443,6 +451,7 @@ 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 */
--
2.10.2
--
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