linux-kernel - Re: [PATCH v2 1/6] debugfs: fix automount d

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 for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <2023112555-squabble-ended-6b8d@gregkh>
Date:   Sat, 25 Nov 2023 19:29:10 +0000
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Johannes Berg <johannes@...solutions.net>
Cc:     linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Rafael J. Wysocki" <rafael@...nel.org>
Subject: Re: [PATCH v2 1/6] debugfs: fix automount d_fsdata usage

On Sat, Nov 25, 2023 at 07:31:47PM +0100, Johannes Berg wrote:
> On Sat, 2023-11-25 at 14:48 +0000, Greg Kroah-Hartman wrote:
> > On Fri, Nov 24, 2023 at 05:25:24PM +0100, Johannes Berg wrote:
> > > From: Johannes Berg <johannes.berg@...el.com>
> > > 
> > > debugfs_create_automount() stores a function pointer in d_fsdata,
> > > but since commit 7c8d469877b1 ("debugfs: add support for more
> > > elaborate ->d_fsdata") debugfs_release_dentry() will free it, now
> > > conditionally on DEBUGFS_FSDATA_IS_REAL_FOPS_BIT, but that's not
> > > set for the function pointer in automount. As a result, removing
> > > an automount dentry would attempt to free the function pointer.
> > > Luckily, the only user of this (tracing) never removes it.
> > > 
> > > Nevertheless, it's safer if we just handle the fsdata in one way,
> > > namely either DEBUGFS_FSDATA_IS_REAL_FOPS_BIT or allocated. Thus,
> > > change the automount to allocate it, and use the real_fops in the
> > > data to indicate whether or not automount is filled, rather than
> > > adding a type tag. At least for now this isn't actually needed,
> > > but the next changes will require it.
> > > 
> > > Also check in debugfs_file_get() that it gets only called
> > > on regular files, just to make things clearer.
> > > 
> > > Signed-off-by: Johannes Berg <johannes.berg@...el.com>
> > > ---
> > > v2: add missing kfree() pointed out by smatch
> > 
> > Acked-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> 
> I have to fix the Kconfig issue in one of the later (wireless) patches,
> but does that mean you'd actually prefer the debugfs changes go through
> the wireless tree, together with the code using it?

I'm all for you taking these through the wireless tree, have fun!

greg k-h