linux-kernel - Re: [PATCH] vfs: Fix possible NULL pointer dereference in inode

lists.openwall.net		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 linux-cve-announce 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]

Message-ID: <20140109223127.GM10323@ZenIV.linux.org.uk>
Date:	Thu, 9 Jan 2014 22:31:27 +0000
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Matthew Wilcox <matthew@....cx>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-fsdevel@...r.kernel.org, Stephen Smalley <sds@...ho.nsa.gov>,
	Christoph Hellwig <hch@...radead.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Eric Paris <eparis@...isplace.org>,
	Theodore Ts'o <tytso@....edu>,
	Dave Chinner <david@...morbit.com>,
	James Morris <james.l.morris@...cle.com>,
	Paul Moore <paul@...l-moore.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	stable <stable@...r.kernel.org>
Subject: Re: [PATCH] vfs: Fix possible NULL pointer dereference in
 inode_permission()

On Thu, Jan 09, 2014 at 04:50:12PM -0500, Steven Rostedt wrote:

> > We'd then have to get rid of all the call_rcu() invocations in individual
> > filesystems' destroy_inode methods, but that doesn't sound like a bad
> > thing to me.

Check what e.g. XFS is doing...

> Which is another reason that I didn't do it, as I didn't know all the
> happenings inside the ->destroy_inode() calls. But yeah, I agree with
> this.
> 
> Also, can iput() sleep? If not then we are OK. Otherwise, we need to be
> careful about any mutex being grabbed in those call backs, as the
> rcu_callback can't sleep either.

iput() definitely can sleep (that's when actual truncation and inode
freeing is done for opened-and-unlinked files - on the final iput() after
close()), but that' irrelevant here - fsnotify_delete_inode() grabs
a bunch of mutexes, which makes calling it from rcu callback no-go.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/