From: Eric Biggers <ebiggers@kernel.org>
To: Waiman Long <longman@redhat.com>
Cc: David Howells <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>,
Chris von Recklinghausen <crecklin@redhat.com>
Subject: Re: [PATCH] KEYS: Don't write out to userspace while holding key semaphore
Date: Thu, 5 Mar 2020 13:16:51 -0800 [thread overview]
Message-ID: <20200305211651.GA225345@gmail.com> (raw)
In-Reply-To: <20200305210640.15315-1-longman@redhat.com>
On Thu, Mar 05, 2020 at 04:06:40PM -0500, Waiman Long wrote:
> diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
> index 9b898c969558..564a4d187329 100644
> --- a/security/keys/keyctl.c
> +++ b/security/keys/keyctl.c
> @@ -846,14 +846,36 @@ long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
> can_read_key:
> ret = -EOPNOTSUPP;
> if (key->type->read) {
> - /* Read the data with the semaphore held (since we might sleep)
> + /*
> + * Read the data with the semaphore held (since we might sleep)
> * to protect against the key being updated or revoked.
> + *
> + * Allocating a temporary buffer to hold the keys before
> + * transferring them to user buffer to avoid potential
> + * deadlock involving page fault and mmap_sem.
> */
> + char *tmpbuf = kmalloc(buflen, GFP_KERNEL);
This is passing an arbitrarily large size from userspace into kmalloc().
- Eric
next prev parent reply other threads:[~2020-03-05 21:17 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-05 21:06 [PATCH] KEYS: Don't write out to userspace while holding key semaphore Waiman Long
2020-03-05 21:16 ` Eric Biggers [this message]
2020-03-05 21:30 ` Waiman Long
2020-03-06 18:40 ` Jarkko Sakkinen
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