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authorJan Kara <jack@suse.cz>2016-12-14 14:40:05 +0100
committerPaul Moore <paul@paul-moore.com>2017-01-03 15:56:38 -0500
commitbe29d20f3f5db1f0b4e49a4f6eeedf840e2bf9b1 (patch)
tree129d3e33fe04b96e2af0b8adf633019a316f10e8
parente3ba730702af370563f66cb610b71aa0ca67955e (diff)
downloadlinux-be29d20f3f5db1f0b4e49a4f6eeedf840e2bf9b1.tar.bz2
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>
-rw-r--r--kernel/audit_tree.c18
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 */