linux-kernel - Re: [PATCH v3 3/6] ima: Detect if lock is held when iint pointer is set in inode security blob

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Message-ID: <910cb84836f8366a566bae7dbe92f0e649d1715c.camel@linux.ibm.com>
Date: Fri, 31 Jan 2025 11:51:56 -0500
From: Mimi Zohar <zohar@...ux.ibm.com>
To: Roberto Sassu <roberto.sassu@...weicloud.com>, corbet@....net,
        viro@...iv.linux.org.uk, brauner@...nel.org, jack@...e.cz,
        dmitry.kasatkin@...il.com, eric.snowberg@...cle.com,
        paul@...l-moore.com, jmorris@...ei.org, serge@...lyn.com
Cc: linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        Roberto Sassu
 <roberto.sassu@...wei.com>
Subject: Re: [PATCH v3 3/6] ima: Detect if lock is held when iint pointer is
 set in inode security blob

On Wed, 2025-01-22 at 18:24 +0100, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@...wei.com>
> 
> IMA stores a pointer of the ima_iint_cache structure, containing integrity
> metadata, in the inode security blob. However, check and assignment of this
> pointer is not atomic, and it might happen that two tasks both see that the
> iint pointer is NULL and try to set it, causing a memory leak.
> 
> Detect if the iint check and assignment is guarded by the iint_lock mutex,
> by adding a lockdep assertion in ima_inode_get().
> 
> Consequently, guard the remaining ima_inode_get() calls, in
> ima_post_create_tmpfile() and ima_post_path_mknod(), to avoid the lockdep
> warnings.
> 
> Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>

Thank you for updating the patch description.  You might also want to mention that
CONFIG_LOCKDEP_DEBUG is required to see the warnings.

Reviewed-by: Mimi Zohar <zohar@...ux.ibm.com>