Re: Another out-of-bound Read in qrtr_endpoint_post in net/qrtr/qrtr.c

[Manivannan Sadhasivam <mani@kernel.org>]

Hi,

On Wed, Aug 18, 2021 at 03:33:38PM +0800, butt3rflyh4ck wrote:
> Here I make a patch for this issue.

[...]

> From 18d9f83f17375785beadbe6a0d0ee59503f65925 Mon Sep 17 00:00:00 2001
> From: butt3rflyh4ck <butterflyhhuangxx@gmail.com>
> Date: Wed, 18 Aug 2021 14:19:38 +0800
> Subject: [PATCH] net: qrtr: fix another OOB Read in qrtr_endpoint_post
> 
> 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: 194ccc88297a ("net: qrtr: Support decoding incoming v2 packets")
> Fixes: ad9d24c9429e ("net: qrtr: fix OOB Read in qrtr_endpoint_post")
> Signed-off-by: butt3rflyh4ck <butterflyhhuangxx@gmail.com>

Thanks for the bug report and the fix. Could you please send the fix as a proper
patch as per: Documentation/process/submitting-patches.rst

Thanks,
Mani

> ---
>  net/qrtr/qrtr.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/qrtr/qrtr.c b/net/qrtr/qrtr.c
> index 171b7f3be6ef..0c30908628ba 100644
> --- a/net/qrtr/qrtr.c
> +++ b/net/qrtr/qrtr.c
> @@ -493,7 +493,7 @@ 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 &&
> -- 
> 2.25.1
>