Messages in this thread Patch in this message | | | From | Miklos Szeredi <> | Subject | [PATCH 2/3] audit: fix refcounting in audit-tree | Date | Wed, 15 Aug 2012 15:49:10 +0200 |
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From: Miklos Szeredi <mszeredi@suse.cz>
Refcounting of fsnotify_mark in audit tree is broken. E.g:
refcount create_chunk alloc_chunk 1 fsnotify_add_mark 2
untag_chunk fsnotify_get_mark 3 fsnotify_destroy_mark audit_tree_freeing_mark 2 fsnotify_put_mark 1 fsnotify_put_mark 0 via destroy_list fsnotify_mark_destroy -1
This was reported by various people as triggering Oops when stopping auditd.
We could just remove the put_mark from audit_tree_freeing_mark() but that would break freeing via inode destruction. So this patch simply omits a put_mark after calling destroy_mark or adds a get_mark before.
The additional get_mark is necessary where there's no other put_mark after fsnotify_destroy_mark() since it assumes that the caller is holding a reference (or the inode is keeping the mark pinned, not the case here AFAICS).
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Reported-by: Valentin Avram <aval13@gmail.com> Reported-by: Peter Moody <pmoody@google.com> Acked-by: Eric Paris <eparis@redhat.com> CC: stable@vger.kernel.org --- kernel/audit_tree.c | 5 ++--- 1 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c index 69a5851..2b2ffff 100644 --- a/kernel/audit_tree.c +++ b/kernel/audit_tree.c @@ -250,7 +250,6 @@ static void untag_chunk(struct node *p) spin_unlock(&hash_lock); spin_unlock(&entry->lock); fsnotify_destroy_mark(entry); - fsnotify_put_mark(entry); goto out; } @@ -293,7 +292,6 @@ static void untag_chunk(struct node *p) spin_unlock(&hash_lock); spin_unlock(&entry->lock); fsnotify_destroy_mark(entry); - fsnotify_put_mark(entry); goto out; Fallback: @@ -332,6 +330,7 @@ static int create_chunk(struct inode *inode, struct audit_tree *tree) spin_unlock(&hash_lock); chunk->dead = 1; spin_unlock(&entry->lock); + fsnotify_get_mark(entry); fsnotify_destroy_mark(entry); fsnotify_put_mark(entry); return 0; @@ -412,6 +411,7 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree) spin_unlock(&chunk_entry->lock); spin_unlock(&old_entry->lock); + fsnotify_get_mark(chunk_entry); fsnotify_destroy_mark(chunk_entry); fsnotify_put_mark(chunk_entry); @@ -445,7 +445,6 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree) spin_unlock(&old_entry->lock); fsnotify_destroy_mark(old_entry); fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */ - fsnotify_put_mark(old_entry); /* and kill it */ return 0; } -- 1.7.7
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