On Thu, 9 Jan 2014 10:31:55 -0500
Eric Paris <eparis@xxxxxxxxxxxxxx> wrote:
> Didn't Al find this/something very similar. I really hate this
I'm not involved with the vfs, so I'm unaware of other solutions
presented. I just hit this now and solving bugs is where I get a chance
to learn about other aspects of the kernel. ;-)
> solution. Why should every LSM try to understand the intimate
> lifetime rules of the parent subsystems? The real problem is that
> inode_free_security() is being called while the inode is still in use.
> While I agree with the assessment, I disagree with the solution. Let
> me try to find where Al and Christoph talked about this....
>
The other obvious solution (but not as trivial to implement) is to call
the security_inode_free() and friends (probably __destroy_inode()
itself) after a synchronize_rcu().
Perhaps something like this?
-- Steve
diff --git a/fs/inode.c b/fs/inode.c
index 4bcdad3..a8f3b88 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -252,16 +252,17 @@ EXPORT_SYMBOL(__destroy_inode);
static void i_callback(struct rcu_head *head)
{
struct inode *inode = container_of(head, struct inode, i_rcu);
+ __destroy_inode(inode);
kmem_cache_free(inode_cachep, inode);
}
static void destroy_inode(struct inode *inode)
{
BUG_ON(!list_empty(&inode->i_lru));
- __destroy_inode(inode);
- if (inode->i_sb->s_op->destroy_inode)
+ if (inode->i_sb->s_op->destroy_inode) {
+ __destroy_inode(inode);
inode->i_sb->s_op->destroy_inode(inode);
- else
+ } else
call_rcu(&inode->i_rcu, i_callback);
}
--
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