linux-kernel - Re: [PATCH v2] tipc: check for null after calling kmemdup

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Message-ID: <0aea60c5-28d5-258a-3a32-bae1895a96ee@redhat.com>
Date:   Wed, 17 Nov 2021 17:06:02 -0500
From:   Jon Maloy <jmaloy@...hat.com>
To:     Tadeusz Struk <tadeusz.struk@...aro.org>, davem@...emloft.net
Cc:     Ying Xue <ying.xue@...driver.com>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        tipc-discussion@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [PATCH v2] tipc: check for null after calling kmemdup

Acked-by: Jon Maloy <jmaloy@...hat.com>

On 11/15/21 11:01, Tadeusz Struk wrote:
> kmemdup can return a null pointer so need to check for it, otherwise
> the null key will be dereferenced later in tipc_crypto_key_xmit as
> can be seen in the trace [1].
>
> Cc: Jon Maloy <jmaloy@...hat.com>
> Cc: Ying Xue <ying.xue@...driver.com>
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: Jakub Kicinski <kuba@...nel.org>
> Cc: netdev@...r.kernel.org
> Cc: tipc-discussion@...ts.sourceforge.net
> Cc: linux-kernel@...r.kernel.org
> Cc: stable@...r.kernel.org # 5.15, 5.14, 5.10
>
> [1] https://syzkaller.appspot.com/bug?id=bca180abb29567b189efdbdb34cbf7ba851c2a58
>
> Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
> Signed-off-by: Tadeusz Struk <tadeusz.struk@...aro.org>
> ---
> Changed in v2:
> - use tipc_aead_free() to free all crytpo tfm instances
>    that might have been allocated before the fail.
> ---
>   net/tipc/crypto.c | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
> index dc60c32bb70d..d293614d5fc6 100644
> --- a/net/tipc/crypto.c
> +++ b/net/tipc/crypto.c
> @@ -597,6 +597,10 @@ static int tipc_aead_init(struct tipc_aead **aead, struct tipc_aead_key *ukey,
>   	tmp->cloned = NULL;
>   	tmp->authsize = TIPC_AES_GCM_TAG_SIZE;
>   	tmp->key = kmemdup(ukey, tipc_aead_key_size(ukey), GFP_KERNEL);
> +	if (!tmp->key) {
> +		tipc_aead_free(&tmp->rcu);
> +		return -ENOMEM;
> +	}
>   	memcpy(&tmp->salt, ukey->key + keylen, TIPC_AES_GCM_SALT_SIZE);
>   	atomic_set(&tmp->users, 0);
>   	atomic64_set(&tmp->seqno, 0);