From: David Howells <dhowells@redhat.com>
To: Waiman Long <longman@redhat.com>
Cc: dhowells@redhat.com,
Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
James Morris <jmorris@namei.org>,
"Serge E. Hallyn" <serge@hallyn.com>,
Mimi Zohar <zohar@linux.ibm.com>,
keyrings@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-integrity@vger.kernel.org,
Sumit Garg <sumit.garg@linaro.org>,
Jerry Snitselaar <jsnitsel@redhat.com>,
Roberto Sassu <roberto.sassu@huawei.com>,
Eric Biggers <ebiggers@google.com>,
Chris von Recklinghausen <crecklin@redhat.com>
Subject: Re: [PATCH v2 2/2] KEYS: Avoid false positive ENOMEM error on key read
Date: Tue, 10 Mar 2020 17:12:23 +0000 [thread overview]
Message-ID: <675400.1583860343@warthog.procyon.org.uk> (raw)
In-Reply-To: <da226448-4b76-0456-4c29-742a1a24fe79@redhat.com>
Waiman Long <longman@redhat.com> wrote:
> That is not as simple as I thought. First of that, there is not an
> equivalent kzvfree() helper to clear the buffer first before clearing.
> Of course, I can do that manually.
Yeah, the actual substance of vfree() may get deferred. It may be worth
adding a kvzfree() that switches between kzfree() and memset(),vfree().
> With patch 2, the allocated buffer length will be max(1024, keylen). The
> security code uses kmalloc() for allocation. If we use kvalloc() here,
> perhaps we should also use that for allocation that can be potentially
> large like that in big_key. What do you think?
Not for big_key: if it's larger than BIG_KEY_FILE_THRESHOLD (~1KiB) it gets
written encrypted into shmem so that it can be swapped out to disk when not in
use.
However, other cases, sure - just be aware that on a 32-bit system,
vmalloc/vmap space is a strictly limited resource.
David
next prev parent reply other threads:[~2020-03-10 17:12 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-08 17:04 [PATCH v2 0/2] KEYS: Read keys to internal buffer & then copy to userspace Waiman Long
2020-03-08 17:04 ` [PATCH v2 1/2] KEYS: Don't write out to userspace while holding key semaphore Waiman Long
2020-03-13 1:04 ` Jarkko Sakkinen
2020-03-13 13:29 ` Waiman Long
2020-03-13 15:28 ` Jarkko Sakkinen
2020-03-13 16:57 ` Waiman Long
2020-03-08 17:04 ` [PATCH v2 2/2] KEYS: Avoid false positive ENOMEM error on key read Waiman Long
2020-03-09 16:32 ` David Howells
2020-03-10 15:45 ` Waiman Long
2020-03-10 15:58 ` Waiman Long
2020-03-10 17:12 ` David Howells [this message]
2020-03-11 15:33 ` Waiman Long
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