lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Date:   Fri, 07 Feb 2020 11:22:04 +0100 (CET)
From:   David Miller <>
Subject: Re: [PATCH net] rxrpc: Fix call RCU cleanup using non-bh-safe locks

From: David Howells <>
Date: Thu, 06 Feb 2020 13:57:40 +0000

> rxrpc_rcu_destroy_call(), which is called as an RCU callback to clean up a
> put call, calls rxrpc_put_connection() which, deep in its bowels, takes a
> number of spinlocks in a non-BH-safe way, including rxrpc_conn_id_lock and
> local->client_conns_lock.  RCU callbacks, however, are normally called from
> softirq context, which can cause lockdep to notice the locking
> inconsistency.
> To get lockdep to detect this, it's necessary to have the connection
> cleaned up on the put at the end of the last of its calls, though normally
> the clean up is deferred.  This can be induced, however, by starting a call
> on an AF_RXRPC socket and then closing the socket without reading the
> reply.
> Fix this by having rxrpc_rcu_destroy_call() punt the destruction to a
> workqueue if in softirq-mode and defer the destruction to process context.
> Note that another way to fix this could be to add a bunch of bh-disable
> annotations to the spinlocks concerned - and there might be more than just
> those two - but that means spending more time with BHs disabled.
> Note also that some of these places were covered by bh-disable spinlocks
> belonging to the rxrpc_transport object, but these got removed without the
> _bh annotation being retained on the next lock in.
> Fixes: 999b69f89241 ("rxrpc: Kill the client connection bundle concept")
> Reported-by:
> Reported-by:
> Signed-off-by: David Howells <>

Applied and queued up for -stable.

Powered by blists - more mailing lists