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* [PATCH] net/bluetooth: Fix bound check in event handling
@ 2019-02-28 19:59 Tomas Bortoli
  2019-03-02 16:46 ` Marcel Holtmann
                   ` (3 more replies)
  0 siblings, 4 replies; 9+ messages in thread
From: Tomas Bortoli @ 2019-02-28 19:59 UTC (permalink / raw)
  To: marcel, johan.hedberg
  Cc: davem, linux-bluetooth, netdev, linux-kernel, syzkaller, Tomas Bortoli

hci_inquiry_result_with_rssi_evt() can perform out of bound reads
on skb->data as a bound check is missing.

Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
Reported-by: syzbot+cec7a50c412a2c03f8f5@syzkaller.appspotmail.com
Reported-by: syzbot+660883c56e2fa65d4497@syzkaller.appspotmail.com
---
Syzkaler reports:
https://syzkaller.appspot.com/bug?id=d708485af9edc3af35f3b4d554e827c6c8bf6b0f
https://syzkaller.appspot.com/bug?id=3acd1155d48a5acc5d76711568b04926945a6885

 net/bluetooth/hci_event.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index ac2826ce162b..aa953d23bb72 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -3983,6 +3983,10 @@ static void hci_inquiry_result_with_rssi_evt(struct hci_dev *hdev,
 		for (; num_rsp; num_rsp--, info++) {
 			u32 flags;
 
+			if ((void *)(info + sizeof(info)) >
+			   (void *)(skb->data + skb->len))
+				break;
+
 			bacpy(&data.bdaddr, &info->bdaddr);
 			data.pscan_rep_mode	= info->pscan_rep_mode;
 			data.pscan_period_mode	= info->pscan_period_mode;
-- 
2.11.0


^ permalink raw reply related	[flat|nested] 9+ messages in thread
* Re: [PATCH] net/bluetooth: Fix bound check in event handling
  2019-02-28 19:59 [PATCH] net/bluetooth: Fix bound check in event handling Tomas Bortoli
@ 2019-03-02 16:46 ` Marcel Holtmann
  2019-03-02 23:17   ` Tomas Bortoli
  2019-03-04 15:04 ` Dan Carpenter
                   ` (2 subsequent siblings)
  3 siblings, 1 reply; 9+ messages in thread
From: Marcel Holtmann @ 2019-03-02 16:46 UTC (permalink / raw)
  To: Tomas Bortoli
  Cc: Johan Hedberg, David S. Miller, open list:BLUETOOTH DRIVERS,
	netdev, linux-kernel, syzkaller

Hi Tomas,

> hci_inquiry_result_with_rssi_evt() can perform out of bound reads
> on skb->data as a bound check is missing.
> 
> Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
> Reported-by: syzbot+cec7a50c412a2c03f8f5@syzkaller.appspotmail.com
> Reported-by: syzbot+660883c56e2fa65d4497@syzkaller.appspotmail.com
> ---
> Syzkaler reports:
> https://syzkaller.appspot.com/bug?id=d708485af9edc3af35f3b4d554e827c6c8bf6b0f
> https://syzkaller.appspot.com/bug?id=3acd1155d48a5acc5d76711568b04926945a6885
> 
> net/bluetooth/hci_event.c | 4 ++++
> 1 file changed, 4 insertions(+)
> 
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index ac2826ce162b..aa953d23bb72 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -3983,6 +3983,10 @@ static void hci_inquiry_result_with_rssi_evt(struct hci_dev *hdev,
> 		for (; num_rsp; num_rsp--, info++) {
> 			u32 flags;
> 
> +			if ((void *)(info + sizeof(info)) >
> +			   (void *)(skb->data + skb->len))
> +				break;
> +

first of all, the loop exists twice here. If one is vulnerable, then the second is a well. And second, can we not just do this inside the for-condition check or a lot simpler than this void casting fun.

Regards

Marcel


^ permalink raw reply	[flat|nested] 9+ messages in thread
* Re: [PATCH] net/bluetooth: Fix bound check in event handling
  2019-03-02 16:46 ` Marcel Holtmann
@ 2019-03-02 23:17   ` Tomas Bortoli
  0 siblings, 0 replies; 9+ messages in thread
From: Tomas Bortoli @ 2019-03-02 23:17 UTC (permalink / raw)
  To: Marcel Holtmann
  Cc: Johan Hedberg, David S. Miller, open list:BLUETOOTH DRIVERS,
	netdev, linux-kernel, syzkaller

Hi Marcel,

On 3/2/19 5:46 PM, Marcel Holtmann wrote:
> Hi Tomas,
> 
>> hci_inquiry_result_with_rssi_evt() can perform out of bound reads
>> on skb->data as a bound check is missing.
>>
>> Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
>> Reported-by: syzbot+cec7a50c412a2c03f8f5@syzkaller.appspotmail.com
>> Reported-by: syzbot+660883c56e2fa65d4497@syzkaller.appspotmail.com
>> ---
>> Syzkaler reports:
>> https://syzkaller.appspot.com/bug?id=d708485af9edc3af35f3b4d554e827c6c8bf6b0f
>> https://syzkaller.appspot.com/bug?id=3acd1155d48a5acc5d76711568b04926945a6885
>>
>> net/bluetooth/hci_event.c | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
>> index ac2826ce162b..aa953d23bb72 100644
>> --- a/net/bluetooth/hci_event.c
>> +++ b/net/bluetooth/hci_event.c
>> @@ -3983,6 +3983,10 @@ static void hci_inquiry_result_with_rssi_evt(struct hci_dev *hdev,
>> 		for (; num_rsp; num_rsp--, info++) {
>> 			u32 flags;
>>
>> +			if ((void *)(info + sizeof(info)) >
>> +			   (void *)(skb->data + skb->len))
>> +				break;
>> +
> 
> first of all, the loop exists twice here. If one is vulnerable, then the second is a well. And second, can we not just do this inside the for-condition check or a lot simpler than this void casting fun.
> 

1. The other for loop is not vulnerable because of the `if` that wraps
the loops. Unfortunately the condition only provides bound checking for
the "else" branch.

2. Sure. I was just getting some compiler warning like "calculated value
but unused" when putting the additional condition. By the way I am
curious to see how to avoid this void casting.

Regards,
Tomas




^ permalink raw reply	[flat|nested] 9+ messages in thread
* Re: [PATCH] net/bluetooth: Fix bound check in event handling
  2019-02-28 19:59 [PATCH] net/bluetooth: Fix bound check in event handling Tomas Bortoli
  2019-03-02 16:46 ` Marcel Holtmann
@ 2019-03-04 15:04 ` Dan Carpenter
  2019-03-04 19:58   ` Tomas Bortoli
  2019-03-04 20:20 ` Tomas Bortoli
  2019-03-30  7:17 ` Dan Carpenter
  3 siblings, 1 reply; 9+ messages in thread
From: Dan Carpenter @ 2019-03-04 15:04 UTC (permalink / raw)
  To: kbuild, Tomas Bortoli
  Cc: kbuild-all, marcel, johan.hedberg, davem, linux-bluetooth,
	netdev, linux-kernel, syzkaller, Tomas Bortoli

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) >

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

^ permalink raw reply	[flat|nested] 9+ messages in thread
* Re: [PATCH] net/bluetooth: Fix bound check in event handling
  2019-03-04 15:04 ` Dan Carpenter
@ 2019-03-04 19:58   ` Tomas Bortoli
  0 siblings, 0 replies; 9+ messages in thread
From: Tomas Bortoli @ 2019-03-04 19:58 UTC (permalink / raw)
  To: Dan Carpenter, kbuild
  Cc: kbuild-all, marcel, johan.hedberg, davem, linux-bluetooth,
	netdev, linux-kernel, syzkaller

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

^ permalink raw reply	[flat|nested] 9+ messages in thread
* [PATCH] net/bluetooth: Fix bound check in event handling
  2019-02-28 19:59 [PATCH] net/bluetooth: Fix bound check in event handling Tomas Bortoli
  2019-03-02 16:46 ` Marcel Holtmann
  2019-03-04 15:04 ` Dan Carpenter
@ 2019-03-04 20:20 ` Tomas Bortoli
  2019-03-30  7:17 ` Dan Carpenter
  3 siblings, 0 replies; 9+ messages in thread
From: Tomas Bortoli @ 2019-03-04 20:20 UTC (permalink / raw)
  To: marcel, johan.hedberg
  Cc: davem, linux-bluetooth, netdev, linux-kernel, syzkaller, Tomas Bortoli

hci_inquiry_result_with_rssi_evt() can perform out of bound reads
on skb->data as a bound check is missing.

Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
Reported-by: syzbot+cec7a50c412a2c03f8f5@syzkaller.appspotmail.com
Reported-by: syzbot+660883c56e2fa65d4497@syzkaller.appspotmail.com
---
v2: 
 - changed sizeof(info) into sizeof(*info), as it should be. 
 - simplified expression in if

 net/bluetooth/hci_event.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index ac2826ce162b..4cbad1e1a322 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -3978,11 +3978,15 @@ static void hci_inquiry_result_with_rssi_evt(struct hci_dev *hdev,
 
 	if ((skb->len - 1) / num_rsp != sizeof(struct inquiry_info_with_rssi)) {
 		struct inquiry_info_with_rssi_and_pscan_mode *info;
+		void *data_end = (void *)skb->data + skb->len;
 		info = (void *) (skb->data + 1);
 
 		for (; num_rsp; num_rsp--, info++) {
 			u32 flags;
 
+			if ((void *)info + sizeof(*info) > data_end)
+				break;
+
 			bacpy(&data.bdaddr, &info->bdaddr);
 			data.pscan_rep_mode	= info->pscan_rep_mode;
 			data.pscan_period_mode	= info->pscan_period_mode;
-- 
2.11.0


^ permalink raw reply related	[flat|nested] 9+ messages in thread
* Re: [PATCH] net/bluetooth: Fix bound check in event handling
  2019-02-28 19:59 [PATCH] net/bluetooth: Fix bound check in event handling Tomas Bortoli
                   ` (2 preceding siblings ...)
  2019-03-04 20:20 ` Tomas Bortoli
@ 2019-03-30  7:17 ` Dan Carpenter
  2019-03-30  8:23   ` [kbuild] " Dan Carpenter
  2019-03-30 22:37   ` Tomas Bortoli
  3 siblings, 2 replies; 9+ messages in thread
From: Dan Carpenter @ 2019-03-30  7:17 UTC (permalink / raw)
  To: kbuild, Tomas Bortoli
  Cc: kbuild-all, marcel, johan.hedberg, davem, linux-bluetooth,
	netdev, linux-kernel, syzkaller, Tomas Bortoli

[ This is an old warning.  Sorry for missing it earlier.  I would have
  caught it when the code was merged as well so there was no real risk
  but it's just awkward.  ]

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

6039aa73 Gustavo Padovan 2012-05-23  3963  static void hci_inquiry_result_with_rssi_evt(struct hci_dev *hdev,
807deac2 Gustavo Padovan 2012-05-17  3964  					     struct sk_buff *skb)
a9de9248 Marcel Holtmann 2007-10-20  3965  {
a9de9248 Marcel Holtmann 2007-10-20  3966  	struct inquiry_data data;
a9de9248 Marcel Holtmann 2007-10-20  3967  	int num_rsp = *((__u8 *) skb->data);
a9de9248 Marcel Holtmann 2007-10-20  3968  
a9de9248 Marcel Holtmann 2007-10-20  3969  	BT_DBG("%s num_rsp %d", hdev->name, num_rsp);
a9de9248 Marcel Holtmann 2007-10-20  3970  
a9de9248 Marcel Holtmann 2007-10-20  3971  	if (!num_rsp)
a9de9248 Marcel Holtmann 2007-10-20  3972  		return;
a9de9248 Marcel Holtmann 2007-10-20  3973  
d7a5a11d Marcel Holtmann 2015-03-13  3974  	if (hci_dev_test_flag(hdev, HCI_PERIODIC_INQ))
1519cc17 Andre Guedes    2012-03-21  3975  		return;
1519cc17 Andre Guedes    2012-03-21  3976  
a9de9248 Marcel Holtmann 2007-10-20  3977  	hci_dev_lock(hdev);
a9de9248 Marcel Holtmann 2007-10-20  3978  
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 should be (void *)info + sizeof(info).  The code you have will
break for valid uses because the pointer math error.  I notice that
this isn't merged into linux-next, but it does seem required.  I am
writing a similar fix for a different function.

Another way to write this would be:

		if ((u8 *)(info + 1) > &skb->data[skb->len]) {


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  
af58925c Marcel Holtmann 2014-07-01  3999  			flags = hci_inquiry_cache_update(hdev, &data, false);
af58925c Marcel Holtmann 2014-07-01  4000  
48264f06 Johan Hedberg   2011-11-09  4001  			mgmt_device_found(hdev, &info->bdaddr, ACL_LINK, 0x00,
e17acd40 Johan Hedberg   2011-03-30  4002  					  info->dev_class, info->rssi,
af58925c Marcel Holtmann 2014-07-01  4003  					  flags, NULL, 0, NULL, 0);
a9de9248 Marcel Holtmann 2007-10-20  4004  		}
a9de9248 Marcel Holtmann 2007-10-20  4005  	} else {

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

^ permalink raw reply	[flat|nested] 9+ messages in thread
* Re: [kbuild] [PATCH] net/bluetooth: Fix bound check in event handling
  2019-03-30  7:17 ` Dan Carpenter
@ 2019-03-30  8:23   ` Dan Carpenter
  2019-03-30 22:37   ` Tomas Bortoli
  1 sibling, 0 replies; 9+ messages in thread
From: Dan Carpenter @ 2019-03-30  8:23 UTC (permalink / raw)
  To: kbuild, Tomas Bortoli
  Cc: johan.hedberg, netdev, marcel, linux-kernel, linux-bluetooth,
	syzkaller, kbuild-all, davem

On Sat, Mar 30, 2019 at 10:17:57AM +0300, Dan Carpenter wrote:
> [ This is an old warning.  Sorry for missing it earlier.  I would have
>   caught it when the code was merged as well so there was no real risk
>   but it's just awkward.  ]
> 
> 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
> 
> 6039aa73 Gustavo Padovan 2012-05-23  3963  static void hci_inquiry_result_with_rssi_evt(struct hci_dev *hdev,
> 807deac2 Gustavo Padovan 2012-05-17  3964  					     struct sk_buff *skb)
> a9de9248 Marcel Holtmann 2007-10-20  3965  {
> a9de9248 Marcel Holtmann 2007-10-20  3966  	struct inquiry_data data;
> a9de9248 Marcel Holtmann 2007-10-20  3967  	int num_rsp = *((__u8 *) skb->data);
> a9de9248 Marcel Holtmann 2007-10-20  3968  
> a9de9248 Marcel Holtmann 2007-10-20  3969  	BT_DBG("%s num_rsp %d", hdev->name, num_rsp);
> a9de9248 Marcel Holtmann 2007-10-20  3970  
> a9de9248 Marcel Holtmann 2007-10-20  3971  	if (!num_rsp)
> a9de9248 Marcel Holtmann 2007-10-20  3972  		return;
> a9de9248 Marcel Holtmann 2007-10-20  3973  
> d7a5a11d Marcel Holtmann 2015-03-13  3974  	if (hci_dev_test_flag(hdev, HCI_PERIODIC_INQ))
> 1519cc17 Andre Guedes    2012-03-21  3975  		return;
> 1519cc17 Andre Guedes    2012-03-21  3976  
> a9de9248 Marcel Holtmann 2007-10-20  3977  	hci_dev_lock(hdev);
> a9de9248 Marcel Holtmann 2007-10-20  3978  
> 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 should be (void *)info + sizeof(info).  The code you have will
                                ^^^^^^^^^^^^
				sizeof(*info)
Sorry...

regards,
dan carpenter


^ permalink raw reply	[flat|nested] 9+ messages in thread
* Re: [PATCH] net/bluetooth: Fix bound check in event handling
  2019-03-30  7:17 ` Dan Carpenter
  2019-03-30  8:23   ` [kbuild] " Dan Carpenter
@ 2019-03-30 22:37   ` Tomas Bortoli
  1 sibling, 0 replies; 9+ messages in thread
From: Tomas Bortoli @ 2019-03-30 22:37 UTC (permalink / raw)
  To: Dan Carpenter, kbuild
  Cc: kbuild-all, marcel, johan.hedberg, davem, linux-bluetooth,
	netdev, linux-kernel, syzkaller

Hi Dan,

On 3/30/19 8:17 AM, Dan Carpenter wrote:
> [ This is an old warning.  Sorry for missing it earlier.  I would have
>   caught it when the code was merged as well so there was no real risk
>   but it's just awkward.  ]
> 
> 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
> 
> 6039aa73 Gustavo Padovan 2012-05-23  3963  static void hci_inquiry_result_with_rssi_evt(struct hci_dev *hdev,
> 807deac2 Gustavo Padovan 2012-05-17  3964  					     struct sk_buff *skb)
> a9de9248 Marcel Holtmann 2007-10-20  3965  {
> a9de9248 Marcel Holtmann 2007-10-20  3966  	struct inquiry_data data;
> a9de9248 Marcel Holtmann 2007-10-20  3967  	int num_rsp = *((__u8 *) skb->data);
> a9de9248 Marcel Holtmann 2007-10-20  3968  
> a9de9248 Marcel Holtmann 2007-10-20  3969  	BT_DBG("%s num_rsp %d", hdev->name, num_rsp);
> a9de9248 Marcel Holtmann 2007-10-20  3970  
> a9de9248 Marcel Holtmann 2007-10-20  3971  	if (!num_rsp)
> a9de9248 Marcel Holtmann 2007-10-20  3972  		return;
> a9de9248 Marcel Holtmann 2007-10-20  3973  
> d7a5a11d Marcel Holtmann 2015-03-13  3974  	if (hci_dev_test_flag(hdev, HCI_PERIODIC_INQ))
> 1519cc17 Andre Guedes    2012-03-21  3975  		return;
> 1519cc17 Andre Guedes    2012-03-21  3976  
> a9de9248 Marcel Holtmann 2007-10-20  3977  	hci_dev_lock(hdev);
> a9de9248 Marcel Holtmann 2007-10-20  3978  
> 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 should be (void *)info + sizeof(info).  The code you have will
> break for valid uses because the pointer math error.  I notice that
> this isn't merged into linux-next, but it does seem required.  I am
> writing a similar fix for a different function.
> 
> Another way to write this would be:
> 
> 		if ((u8 *)(info + 1) > &skb->data[skb->len]) {

Yeah it hasn't been accepted afaik. Why just + 1 ? Also,
&skb->data[skb->len] is right after the last byte so the > should rather
be a >=, I think.

your code looks better (as per pointer casting) but is logically
different from what I proposed with v2:

https://lkml.org/lkml/2019/3/4/892

I think the bound check should validate that there is enough data from
the info pointer to read an entire struct
inquiry_info_with_rssi_and_pscan_mode.

Best regards,
Tomas


^ permalink raw reply	[flat|nested] 9+ messages in thread
end of thread, other threads:[~2019-03-30 22:37 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-02-28 19:59 [PATCH] net/bluetooth: Fix bound check in event handling Tomas Bortoli
2019-03-02 16:46 ` Marcel Holtmann
2019-03-02 23:17   ` Tomas Bortoli
2019-03-04 15:04 ` Dan Carpenter
2019-03-04 19:58   ` Tomas Bortoli
2019-03-04 20:20 ` Tomas Bortoli
2019-03-30  7:17 ` Dan Carpenter
2019-03-30  8:23   ` [kbuild] " Dan Carpenter
2019-03-30 22:37   ` Tomas Bortoli

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