net: qrtr: fix OOB Read in qrtr_endpoint_post

stable inclusion
from linux-4.19.196
commit f8111c0d7ed42ede41a3d0d393b104de0730a8a6
CVE: CVE-2021-3743

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

[ Upstream commit ad9d24c9 ]

Syzbot reported slab-out-of-bounds Read in
qrtr_endpoint_post. The problem was in wrong
_size_ type:

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

If size from qrtr_hdr is 4294967293 (0xfffffffd), the result of
ALIGN(size, 4) will be 0. In case of len == hdrlen and size == 4294967293
in header this check won't fail and

	skb_put_data(skb, data + hdrlen, size);

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

Fixes: 194ccc88 ("net: qrtr: Support decoding incoming v2 packets")
Reported-and-tested-by: syzbot+1917d778024161609247@syzkaller.appspotmail.com
Signed-off-by: NPavel Skripkin <paskripkin@gmail.com>
Reviewed-by: NBjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NSasha Levin <sashal@kernel.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

@@ -262,7 +262,7 @@ int qrtr_endpoint_post(struct qrtr_endpoint *ep, const void *data, size_t len)
 	const struct qrtr_hdr_v2 *v2;
 	struct sk_buff *skb;
 	struct qrtr_cb *cb;
-	unsigned int size;
+	size_t size;
 	unsigned int ver;
 	size_t hdrlen;