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] [thread-next>] [day] [month] [year] [list]
Date:   Fri, 5 Mar 2021 10:18:16 -0500
From:   "Theodore Ts'o" <>
To:     Alexander Lochmann <>
Cc:     Horst Schirmeier <>,
        Jan Kara <>, Jan Kara <>,,
Subject: Re: [RFC] inode.i_opflags - Usage of two different locking schemes

On Fri, Mar 05, 2021 at 02:10:09PM +0100, Alexander Lochmann wrote:
> Hi folks,
> I've stumbled across an interesting locking scheme. It's related to struct
> inode, more precisely it is an mqueue inode.
> Our results show that inode:mqueue.i_opflags is read with i_rwsem being
> hold.
> In d_flags_for_inode, and do_inode_permission the i_lock is used to read and
> write i_opflags.
> Is this a real locking scheme? Is a lock needed to access i_opflags at all?
> What is the magic behind this contradiction?
> I've put the report of the counterexamples on our webserver:
> It contains the stacktraces leading to those accesses, and the locks that
> were actually held.

1)  I don't see where i_opflags is being read in ipc/mqueue.c at all,
either with or without i_rwsem.

2)  I'm not sure what this has to do with ext4?

        	    	      	       	  - Ted

Powered by blists - more mailing lists