linux-kernel - Re: [PATCH] net/bluetooth: Fix bound check in event handling

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Date:   Mon, 4 Mar 2019 20:58:51 +0100
From:   Tomas Bortoli <tomasbortoli@...il.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>, kbuild@...org
Cc:     kbuild-all@...org, marcel@...tmann.org, johan.hedberg@...il.com,
        davem@...emloft.net, linux-bluetooth@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzkaller@...glegroups.com
Subject: Re: [PATCH] net/bluetooth: Fix bound check in event handling

Hi Dan,

On 3/4/19 4:04 PM, Dan Carpenter wrote:
> Hi Tomas,
> 
> url:    https://github.com/0day-ci/linux/commits/Tomas-Bortoli/net-bluetooth-Fix-bound-check-in-event-handling/20190301-213647
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git master
> 
> smatch warnings:
> net/bluetooth/hci_event.c:3986 hci_inquiry_result_with_rssi_evt() warn: potential pointer math issue ('info' is a 120 bit pointer)
> 
> # https://github.com/0day-ci/linux/commit/00305742c021794f147b348d45eb10ea26e5a514
> git remote add linux-review https://github.com/0day-ci/linux
> git remote update linux-review
> git checkout 00305742c021794f147b348d45eb10ea26e5a514
> vim +3986 net/bluetooth/hci_event.c
> 
> a9de9248 Marcel Holtmann 2007-10-20  3979  	if ((skb->len - 1) / num_rsp != sizeof(struct inquiry_info_with_rssi)) {
> 138d22ef Szymon Janc     2011-02-17  3980  		struct inquiry_info_with_rssi_and_pscan_mode *info;
>                                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 
> 138d22ef Szymon Janc     2011-02-17  3981  		info = (void *) (skb->data + 1);
> a9de9248 Marcel Holtmann 2007-10-20  3982  
> e17acd40 Johan Hedberg   2011-03-30  3983  		for (; num_rsp; num_rsp--, info++) {
> af58925c Marcel Holtmann 2014-07-01  3984  			u32 flags;
> af58925c Marcel Holtmann 2014-07-01  3985  
> 00305742 Tomas Bortoli   2019-02-28 @3986  			if ((void *)(info + sizeof(info)) >
>                                                                              ^^^^^^^^^^^^^^^^^^^
> This is a pointer math bug.  The options to fix it are:
> 
> 		if ((void *)info + sizeof(info) >

Yes, also sizeof(info) should be sizeof(*info)..

> 
> Or:
> 		if ((void *)(info + 1) >
> 
> 
> 00305742 Tomas Bortoli   2019-02-28  3987  			   (void *)(skb->data + skb->len))
> 00305742 Tomas Bortoli   2019-02-28  3988  				break;
> 00305742 Tomas Bortoli   2019-02-28  3989  
> a9de9248 Marcel Holtmann 2007-10-20  3990  			bacpy(&data.bdaddr, &info->bdaddr);
> a9de9248 Marcel Holtmann 2007-10-20  3991  			data.pscan_rep_mode	= info->pscan_rep_mode;
> a9de9248 Marcel Holtmann 2007-10-20  3992  			data.pscan_period_mode	= info->pscan_period_mode;
> a9de9248 Marcel Holtmann 2007-10-20  3993  			data.pscan_mode		= info->pscan_mode;
> a9de9248 Marcel Holtmann 2007-10-20  3994  			memcpy(data.dev_class, info->dev_class, 3);
> a9de9248 Marcel Holtmann 2007-10-20  3995  			data.clock_offset	= info->clock_offset;
> a9de9248 Marcel Holtmann 2007-10-20  3996  			data.rssi		= info->rssi;
> 41a96212 Marcel Holtmann 2008-07-14  3997  			data.ssp_mode		= 0x00;
> 3175405b Johan Hedberg   2012-01-04  3998  
> 
> regards,
> dan carpenter
> 
> ---
> 0-DAY kernel test infrastructure                Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
> 

regards,
Tomas