netdev - Re: [PATCH net-next v5] net/ncsi: Extend NC-SI Netlink interface to allow user space to send NC-SI command

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <e26c7aa664a2dad4f5bcf4efaa1b3eb655548b01.camel@mendozajonas.com>
Date:   Thu, 11 Oct 2018 14:55:08 +1100
From:   Samuel Mendoza-Jonas <sam@...dozajonas.com>
To:     Justin.Lee1@...l.com, joel@....id.au
Cc:     linux-aspeed@...ts.ozlabs.org, netdev@...r.kernel.org,
        openbmc@...ts.ozlabs.org, amithash@...com, christian@....nu,
        vijaykhemka@...com
Subject: Re: [PATCH net-next v5] net/ncsi: Extend NC-SI Netlink interface to
 allow user space to send NC-SI command

On Wed, 2018-10-10 at 18:11 +0000, Justin.Lee1@...l.com wrote:
<snip>
> +
> +	len = nla_len(info->attrs[NCSI_ATTR_DATA]);
> +	if (len < sizeof(struct ncsi_pkt_hdr)) {
> +		netdev_info(ndp->ndev.dev, "NCSI: no command to send %u\n",
> +			    package_id);
> +		ret = -EINVAL;
> +		goto out_netlink;
> +	} else {
> +		data = (unsigned char *)nla_data(info->attrs[NCSI_ATTR_DATA]);
> +	}

I only just noticed this, the call to nla_len() can cause a null-dereference if
the NCSI_ATTR_DATA attribute isn't present; we need to make sure it exists
before accessing it in info->attrs.

eg:

root@...om2-bmc:~# ./ncsi-netlink -l 2 -p 0 -c 0 --cmd
[   81.399837] Unable to handle kernel NULL pointer dereference at virtual address 00000000
[   81.409092] pgd = ddaa9fa6
[   81.413084] [00000000] *pgd=9702c831, *pte=00000000, *ppte=00000000
[   81.420729] Internal error: Oops: 17 [#1] ARM
[   81.426447] CPU: 0 PID: 1028 Comm: ncsi-netlink Not tainted 4.18.8-sammj-00144-gbc129f31bfa5 #12
...
[   81.874434] Kernel panic - not syncing: Fatal exception

Cheers,
Sam