From: Dan Carpenter <dan.carpenter@oracle.com>
To: Colin King <colin.king@canonical.com>
Cc: James Bottomley <jejb@linux.ibm.com>,
Jarkko Sakkinen <jarkko@kernel.org>,
Mimi Zohar <zohar@linux.ibm.com>,
David Howells <dhowells@redhat.com>,
James Morris <jmorris@namei.org>,
"Serge E . Hallyn" <serge@hallyn.com>,
linux-integrity@vger.kernel.org, keyrings@vger.kernel.org,
linux-security-module@vger.kernel.org,
kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] security: keys: trusted: Fix memory leaks on allocated blob
Date: Mon, 26 Jul 2021 11:50:51 +0300 [thread overview]
Message-ID: <20210726085051.GG1931@kadam> (raw)
In-Reply-To: <20210723172121.156687-1-colin.king@canonical.com>
On Fri, Jul 23, 2021 at 06:21:21PM +0100, Colin King wrote:
> @@ -441,6 +449,10 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
> rc = -EPERM;
>
> return rc;
> +
> +err:
> + kfree(blob);
This needs to be:
if (blob != payload->blob)
kfree(blob);
Otherwise it leads to a use after free.
> + return rc;
> }
How this is allocated is pretty scary looking!
security/keys/trusted-keys/trusted_tpm2.c
96 static int tpm2_key_decode(struct trusted_key_payload *payload,
97 struct trusted_key_options *options,
98 u8 **buf)
99 {
100 int ret;
101 struct tpm2_key_context ctx;
102 u8 *blob;
103
104 memset(&ctx, 0, sizeof(ctx));
105
106 ret = asn1_ber_decoder(&tpm2key_decoder, &ctx, payload->blob,
107 payload->blob_len);
108 if (ret < 0)
109 return ret;
Old form?
110
111 if (ctx.priv_len + ctx.pub_len > MAX_BLOB_SIZE)
112 return -EINVAL;
It's really scary to me that if the lengths are too large for kmalloc()
then we just use "payload->blob".
113
114 blob = kmalloc(ctx.priv_len + ctx.pub_len + 4, GFP_KERNEL);
blob is allocated here.
115 if (!blob)
116 return -ENOMEM;
117
118 *buf = blob;
119 options->keyhandle = ctx.parent;
120
121 memcpy(blob, ctx.priv, ctx.priv_len);
122 blob += ctx.priv_len;
123
124 memcpy(blob, ctx.pub, ctx.pub_len);
125
126 return 0;
127 }
[ snip ]
371 u32 attrs;
372
373 rc = tpm2_key_decode(payload, options, &blob);
374 if (rc) {
375 /* old form */
376 blob = payload->blob;
^^^^^^^^^^^^^^^^^^^^
377 payload->old_format = 1;
378 }
379
regards,
dan carpenter
next prev parent reply other threads:[~2021-07-26 8:51 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-23 17:21 [PATCH] security: keys: trusted: Fix memory leaks on allocated blob Colin King
2021-07-26 5:33 ` Sumit Garg
2021-07-26 8:50 ` Dan Carpenter [this message]
2021-07-26 10:56 ` Colin Ian King
2021-07-27 3:05 ` Jarkko Sakkinen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210726085051.GG1931@kadam \
--to=dan.carpenter@oracle.com \
--cc=colin.king@canonical.com \
--cc=dhowells@redhat.com \
--cc=jarkko@kernel.org \
--cc=jejb@linux.ibm.com \
--cc=jmorris@namei.org \
--cc=kernel-janitors@vger.kernel.org \
--cc=keyrings@vger.kernel.org \
--cc=linux-integrity@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=serge@hallyn.com \
--cc=zohar@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).