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

[Mimi Zohar]

On Wed, 2025-01-22 at 18:24 +0100, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu at huawei.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 at huawei.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 at linux.ibm.com>