From: Miklos Szeredi <miklos@szeredi.hu>
To: torvalds@linux-foundation.org
Cc: eparis@redhat.com, viro@ZenIV.linux.org.uk,
linux-kernel@vger.kernel.org, mszeredi@suse.cz,
stable@vger.kernel.org
Subject: [PATCH 2/3] audit: fix refcounting in audit-tree
Date: Tue, 21 Aug 2012 21:03:58 +0200 [thread overview]
Message-ID: <1345575839-9389-3-git-send-email-miklos@szeredi.hu> (raw)
In-Reply-To: <1345575839-9389-1-git-send-email-miklos@szeredi.hu>
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
next prev parent reply other threads:[~2012-08-21 19:04 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-21 19:03 [PATCH 0/3] audit-tree fixes Miklos Szeredi
2012-08-21 19:03 ` [PATCH 1/3] audit: don't free_chunk() after fsnotify_add_mark() Miklos Szeredi
2012-08-21 19:03 ` Miklos Szeredi [this message]
2012-08-21 19:03 ` [PATCH 3/3] audit: clean up refcounting in audit-tree Miklos Szeredi
2012-08-21 19:37 ` Linus Torvalds
-- strict thread matches above, loose matches on Subject: below --
2012-08-15 13:49 [PATCH 0/3] audit-tree fixes (resend) Miklos Szeredi
2012-08-15 13:49 ` [PATCH 2/3] audit: fix refcounting in audit-tree Miklos Szeredi
2012-06-25 17:46 [PATCH 0/3] audit-tree fixes Miklos Szeredi
2012-06-25 17:46 ` [PATCH 2/3] audit: fix refcounting in audit-tree Miklos Szeredi
2012-07-06 17:52 ` Eric Paris
2012-07-11 22:24 ` Miklos Szeredi
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