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

[Jon Maloy <jmaloy@redhat.com>]

Acked-by: Jon Maloy <jmaloy@redhat.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@redhat.com>
> Cc: Ying Xue <ying.xue@windriver.com>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: netdev@vger.kernel.org
> Cc: tipc-discussion@lists.sourceforge.net
> Cc: linux-kernel@vger.kernel.org
> Cc: stable@vger.kernel.org # 5.15, 5.14, 5.10
>
> [1] https://syzkaller.appspot.com/bug?id=bca180abb29567b189efdbdb34cbf7ba851c2a58
>
> Reported-by: Dmitry Vyukov <dvyukov@google.com>
> Signed-off-by: Tadeusz Struk <tadeusz.struk@linaro.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);