net: qrtr: fix another OOB Read in qrtr_endpoint_post

stable inclusion
from linux-4.19.206
commit ce7d8be2eaa4cab3032e256d154d1c33843d2367
CVE: CVE-2021-3743

--------------------------------

commit 7e78c597 upstream.

This check was incomplete, did not consider size is 0:

	if (len != ALIGN(size, 4) + hdrlen)
                    goto err;

if size from qrtr_hdr is 0, the result of ALIGN(size, 4)
will be 0, In case of len == hdrlen and size == 0
in header this check won't fail and

	if (cb->type == QRTR_TYPE_NEW_SERVER) {
                /* Remote node endpoint can bridge other distant nodes */
                const struct qrtr_ctrl_pkt *pkt = data + hdrlen;

                qrtr_node_assign(node, le32_to_cpu(pkt->server.node));
        }

will also read out of bound from data, which is hdrlen allocated block.

Fixes: 194ccc88 ("net: qrtr: Support decoding incoming v2 packets")
Fixes: ad9d24c9 ("net: qrtr: fix OOB Read in qrtr_endpoint_post")
Signed-off-by: NXiaolong Huang <butterflyhuangxx@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Reviewed-by: NXiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: NYue Haibing <yuehaibing@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

net/qrtr/qrtr.c

@@ -315,7 +315,7 @@ int qrtr_endpoint_post(struct qrtr_endpoint *ep, const void *data, size_t len)
 		goto err;
 	}
 
-	if (len != ALIGN(size, 4) + hdrlen)
+	if (!size || len != ALIGN(size, 4) + hdrlen)
 		goto err;
 
 	if (cb->dst_port != QRTR_PORT_CTRL && cb->type != QRTR_TYPE_DATA)