From: Eric Biggers <ebiggers@kernel.org>
To: dinghao.liu@zju.edu.cn
Cc: kjlu@umn.edu, Mimi Zohar <zohar@linux.ibm.com>,
James Morris <jmorris@namei.org>,
"Serge E. Hallyn" <serge@hallyn.com>,
Dmitry Kasatkin <dmitry.kasatkin@nokia.com>,
linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: Re: [PATCH] evm: Fix memleak in init_desc
Date: Sat, 9 Jan 2021 22:53:38 -0800 [thread overview]
Message-ID: <X/qkcgLg2h8Yxn3a@sol.localdomain> (raw)
In-Reply-To: <5a36a73a.2e704.176eac332ca.Coremail.dinghao.liu@zju.edu.cn>
On Sun, Jan 10, 2021 at 01:27:09PM +0800, dinghao.liu@zju.edu.cn wrote:
> > On Sat, Jan 09, 2021 at 07:33:05PM +0800, Dinghao Liu wrote:
> > > When kmalloc() fails, tmp_tfm allocated by
> > > crypto_alloc_shash() has not been freed, which
> > > leads to memleak.
> > >
> > > Fixes: d46eb3699502b ("evm: crypto hash replaced by shash")
> > > Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
> > > ---
> > > security/integrity/evm/evm_crypto.c | 9 +++++++--
> > > 1 file changed, 7 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
> > > index 168c3b78ac47..39fb31a638ac 100644
> > > --- a/security/integrity/evm/evm_crypto.c
> > > +++ b/security/integrity/evm/evm_crypto.c
> > > @@ -73,7 +73,7 @@ static struct shash_desc *init_desc(char type, uint8_t hash_algo)
> > > {
> > > long rc;
> > > const char *algo;
> > > - struct crypto_shash **tfm, *tmp_tfm;
> > > + struct crypto_shash **tfm, *tmp_tfm = NULL;
> > > struct shash_desc *desc;
> > >
> > > if (type == EVM_XATTR_HMAC) {
> > > @@ -118,13 +118,18 @@ static struct shash_desc *init_desc(char type, uint8_t hash_algo)
> > > alloc:
> > > desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(*tfm),
> > > GFP_KERNEL);
> > > - if (!desc)
> > > + if (!desc) {
> > > + if (tmp_tfm)
> > > + crypto_free_shash(tmp_tfm);
> > > return ERR_PTR(-ENOMEM);
> > > + }
> > >
> > > desc->tfm = *tfm;
> > >
> > > rc = crypto_shash_init(desc);
> > > if (rc) {
> > > + if (tmp_tfm)
> > > + crypto_free_shash(tmp_tfm);
> > > kfree(desc);
> > > return ERR_PTR(rc);
> > > }
> >
> > There's no need to check for NULL before calling crypto_free_shash().
> >
>
> I find there is a crypto_shash_tfm() in the definition of
> crypto_free_shash(). Will this lead to null pointer dereference
> when we use it to free a NULL pointer?
>
No. It does &tfm->base, not tfm->base.
- Eric
next prev parent reply other threads:[~2021-01-10 6:54 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-09 11:33 [PATCH] evm: Fix memleak in init_desc Dinghao Liu
2021-01-09 17:07 ` Eric Biggers
2021-01-10 5:27 ` dinghao.liu
2021-01-10 6:53 ` Eric Biggers [this message]
2021-01-10 7:01 ` dinghao.liu
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